This file is indexed.

/usr/share/doc/graphviz/html/FAQ.html is in graphviz-doc 2.38.0-12ubuntu2.

This file is owned by root:root, with mode 0o644.

The actual contents of the file can be viewed below.

   1
   2
   3
   4
   5
   6
   7
   8
   9
  10
  11
  12
  13
  14
  15
  16
  17
  18
  19
  20
  21
  22
  23
  24
  25
  26
  27
  28
  29
  30
  31
  32
  33
  34
  35
  36
  37
  38
  39
  40
  41
  42
  43
  44
  45
  46
  47
  48
  49
  50
  51
  52
  53
  54
  55
  56
  57
  58
  59
  60
  61
  62
  63
  64
  65
  66
  67
  68
  69
  70
  71
  72
  73
  74
  75
  76
  77
  78
  79
  80
  81
  82
  83
  84
  85
  86
  87
  88
  89
  90
  91
  92
  93
  94
  95
  96
  97
  98
  99
 100
 101
 102
 103
 104
 105
 106
 107
 108
 109
 110
 111
 112
 113
 114
 115
 116
 117
 118
 119
 120
 121
 122
 123
 124
 125
 126
 127
 128
 129
 130
 131
 132
 133
 134
 135
 136
 137
 138
 139
 140
 141
 142
 143
 144
 145
 146
 147
 148
 149
 150
 151
 152
 153
 154
 155
 156
 157
 158
 159
 160
 161
 162
 163
 164
 165
 166
 167
 168
 169
 170
 171
 172
 173
 174
 175
 176
 177
 178
 179
 180
 181
 182
 183
 184
 185
 186
 187
 188
 189
 190
 191
 192
 193
 194
 195
 196
 197
 198
 199
 200
 201
 202
 203
 204
 205
 206
 207
 208
 209
 210
 211
 212
 213
 214
 215
 216
 217
 218
 219
 220
 221
 222
 223
 224
 225
 226
 227
 228
 229
 230
 231
 232
 233
 234
 235
 236
 237
 238
 239
 240
 241
 242
 243
 244
 245
 246
 247
 248
 249
 250
 251
 252
 253
 254
 255
 256
 257
 258
 259
 260
 261
 262
 263
 264
 265
 266
 267
 268
 269
 270
 271
 272
 273
 274
 275
 276
 277
 278
 279
 280
 281
 282
 283
 284
 285
 286
 287
 288
 289
 290
 291
 292
 293
 294
 295
 296
 297
 298
 299
 300
 301
 302
 303
 304
 305
 306
 307
 308
 309
 310
 311
 312
 313
 314
 315
 316
 317
 318
 319
 320
 321
 322
 323
 324
 325
 326
 327
 328
 329
 330
 331
 332
 333
 334
 335
 336
 337
 338
 339
 340
 341
 342
 343
 344
 345
 346
 347
 348
 349
 350
 351
 352
 353
 354
 355
 356
 357
 358
 359
 360
 361
 362
 363
 364
 365
 366
 367
 368
 369
 370
 371
 372
 373
 374
 375
 376
 377
 378
 379
 380
 381
 382
 383
 384
 385
 386
 387
 388
 389
 390
 391
 392
 393
 394
 395
 396
 397
 398
 399
 400
 401
 402
 403
 404
 405
 406
 407
 408
 409
 410
 411
 412
 413
 414
 415
 416
 417
 418
 419
 420
 421
 422
 423
 424
 425
 426
 427
 428
 429
 430
 431
 432
 433
 434
 435
 436
 437
 438
 439
 440
 441
 442
 443
 444
 445
 446
 447
 448
 449
 450
 451
 452
 453
 454
 455
 456
 457
 458
 459
 460
 461
 462
 463
 464
 465
 466
 467
 468
 469
 470
 471
 472
 473
 474
 475
 476
 477
 478
 479
 480
 481
 482
 483
 484
 485
 486
 487
 488
 489
 490
 491
 492
 493
 494
 495
 496
 497
 498
 499
 500
 501
 502
 503
 504
 505
 506
 507
 508
 509
 510
 511
 512
 513
 514
 515
 516
 517
 518
 519
 520
 521
 522
 523
 524
 525
 526
 527
 528
 529
 530
 531
 532
 533
 534
 535
 536
 537
 538
 539
 540
 541
 542
 543
 544
 545
 546
 547
 548
 549
 550
 551
 552
 553
 554
 555
 556
 557
 558
 559
 560
 561
 562
 563
 564
 565
 566
 567
 568
 569
 570
 571
 572
 573
 574
 575
 576
 577
 578
 579
 580
 581
 582
 583
 584
 585
 586
 587
 588
 589
 590
 591
 592
 593
 594
 595
 596
 597
 598
 599
 600
 601
 602
 603
 604
 605
 606
 607
 608
 609
 610
 611
 612
 613
 614
 615
 616
 617
 618
 619
 620
 621
 622
 623
 624
 625
 626
 627
 628
 629
 630
 631
 632
 633
 634
 635
 636
 637
 638
 639
 640
 641
 642
 643
 644
 645
 646
 647
 648
 649
 650
 651
 652
 653
 654
 655
 656
 657
 658
 659
 660
 661
 662
 663
 664
 665
 666
 667
 668
 669
 670
 671
 672
 673
 674
 675
 676
 677
 678
 679
 680
 681
 682
 683
 684
 685
 686
 687
 688
 689
 690
 691
 692
 693
 694
 695
 696
 697
 698
 699
 700
 701
 702
 703
 704
 705
 706
 707
 708
 709
 710
 711
 712
 713
 714
 715
 716
 717
 718
 719
 720
 721
 722
 723
 724
 725
 726
 727
 728
 729
 730
 731
 732
 733
 734
 735
 736
 737
 738
 739
 740
 741
 742
 743
 744
 745
 746
 747
 748
 749
 750
 751
 752
 753
 754
 755
 756
 757
 758
 759
 760
 761
 762
 763
 764
 765
 766
 767
 768
 769
 770
 771
 772
 773
 774
 775
 776
 777
 778
 779
 780
 781
 782
 783
 784
 785
 786
 787
 788
 789
 790
 791
 792
 793
 794
 795
 796
 797
 798
 799
 800
 801
 802
 803
 804
 805
 806
 807
 808
 809
 810
 811
 812
 813
 814
 815
 816
 817
 818
 819
 820
 821
 822
 823
 824
 825
 826
 827
 828
 829
 830
 831
 832
 833
 834
 835
 836
 837
 838
 839
 840
 841
 842
 843
 844
 845
 846
 847
 848
 849
 850
 851
 852
 853
 854
 855
 856
 857
 858
 859
 860
 861
 862
 863
 864
 865
 866
 867
 868
 869
 870
 871
 872
 873
 874
 875
 876
 877
 878
 879
 880
 881
 882
 883
 884
 885
 886
 887
 888
 889
 890
 891
 892
 893
 894
 895
 896
 897
 898
 899
 900
 901
 902
 903
 904
 905
 906
 907
 908
 909
 910
 911
 912
 913
 914
 915
 916
 917
 918
 919
 920
 921
 922
 923
 924
 925
 926
 927
 928
 929
 930
 931
 932
 933
 934
 935
 936
 937
 938
 939
 940
 941
 942
 943
 944
 945
 946
 947
 948
 949
 950
 951
 952
 953
 954
 955
 956
 957
 958
 959
 960
 961
 962
 963
 964
 965
 966
 967
 968
 969
 970
 971
 972
 973
 974
 975
 976
 977
 978
 979
 980
 981
 982
 983
 984
 985
 986
 987
 988
 989
 990
 991
 992
 993
 994
 995
 996
 997
 998
 999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
        "http://www.w3.org/TR/html4/loose.dtd">
<HTML><HEAD><TITLE>Graphviz FAQ 2008-06-06</TITLE>
<META HTTP-EQUIV="content-type" CONTENT="text/html; charset=utf-8">
</HEAD><BODY>
<H1>Graphviz FAQ 2009-09-10</H1>

<A HREF="mailto:gviz-bugs@research.att.com">The Graphviz Project</A>
<p>
<b>Note</b>:
This is not a tutorial; to understand the following, you should
know how to use the basic features of the tools and
languages involved. Please see the
<A HREF="http://www.graphviz.org/Documentation.php">
user guides and documentation</A> for further information or the
<A HREF="http://www.graphviz.org/Resources.php">resources page</A>
for a partial list of compatible tools and packages.

<h2>General</h2>

<A name=Q1 HREF=#Q1>
<B>Q1</A>. Where can I see a list of all the attributes that control dot or neato?</B>

</A>
<P>
See <A HREF="info/attrs.html">
Graph Attributes</A>. There is also information on
<A HREF="info/command.html">
command-line usage</A> and
<A HREF="info/output.html">
output formats</A>.
<p>
<a name="mailinglist"></a>
<A name=Q2 HREF=#Q2>
<B>Q2</A>. Where can I discuss Graphviz?</B>

<p>
We run a mailing list.
<p>
To subscribe or unsubscribe, visit the
<A HREF="https://mailman.research.att.com/mailman/listinfo/graphviz-interest">graphviz-interest</A> <em>mailman</em> control page.  See also the general
<A HREF="http://www.list.org/mailman-member/index.html">
instructions</A> for mailman.
<p>
You can also see the
<A HREF="https://mailman.research.att.com/pipermail/graphviz-interest/">
archive</A>.
<p>
You may wish to use a Yahoo or Hotmail account if you're concerned
about spam. We also run anti-spam filters, and rewrite <tt>@</tt>
as <tt>at</tt> to keep verbatim addresses out of the archive.
<p>
Please, please, please, do not torment the mailing list with beginner's
questions.  First, check this FAQ and the
<A HREF="https://mailman.research.att.com/pipermail/graphviz-interest/">
message archive</A> carefully. 
If you are desperate, or better yet, if you have constructive advice,
please send a message to the <A HREF="https://mailman.research.att.com/mailman/listinfo/graphviz-devel">graphviz-devel mailing list</A>.
<p>
Also, if a program crashes or you get an abort or something strange occurs
and you are fairly comfortable using the tools:
<UL>
<LI>
Check the 
<A HREF="http://www.research.att.com/~erg/graphviz/bugs/openbugs.html"> open
bug list</A> to see if a similar bug has already been reported. You might
also consider checking the
<A HREF="http://www.research.att.com/~erg/graphviz/bugs/buglist.html"> full
bug list</A>, since your bug may have been reported and fixed in the working
version.
<LI>
Submit a <A HREF="http://www.research.att.com/~erg/graphviz/bugform.html">bug 
report</A>. If you prefer, you can download a 
<A HREF="http://www.research.att.com/~erg/graphviz/bugform.txt">report in
text form</A>, fill in the fields, and email it to 
<a href="mailto:gviz-bugs@research.att.com">gviz-bugs@research.att.com</a>.
</UL>
<p>
<A name=Q3 HREF=#Q3>
<B>Q3</A>. I'm trying to make a layout larger. How?</B>

<p>
There are various ways to increase the size of a layout. In doing this,
one has to decide if the sizes of the nodes and text should be 
increased as well.
<p>
One approach is to adjust individual
parameters such as <tt>fontsize, nodesep</tt> and <tt>ranksep</tt>.
For example,
<pre>
           digraph G {
                graph [fontsize=24];
                edge  [fontsize=24];
                node  [fontsize=24];
                ranksep = 1.5;
                nodesep = .25;
                edge [style="setlinewidth(3)"];
                a -&gt; b -&gt; c;
           }
</pre>
If you do this, make sure you are not fighting a conflicting graph
size setting, like <tt>size="6,6"</tt>, which will then scale
everything back down.
<p>
If you are using fdp or neato, increasing the edge len will tend to
expand the layout.
<pre>
        graph G {
           edge [len=3]
           a -- { b c d }
        }
</pre>
For twopi and circo, there are other parameters such as
<tt>ranksep</tt> which can be used. See the 
<A HREF="info/attrs.html">
graph attributes</A>.
<p>
You can also use the <tt>ratio</tt> attribute. If you set the <tt>size</tt>
attribute to the desired drawing size, and then set <tt>ratio=fill</tt>, node
positions are scaled separately in x and y until the drawing fills the
specified <tt>size</tt>. Note that node sizes stay the same. If, instead,
you set <tt>ratio=expand</tt>, the layout is uniformly scaled up in x and y
until at least one dimension fits <tt>size</tt>.
<p>
If you specify the <tt>size</tt> attribute but end it with an exclamation
mark (!), the final drawing will be scaled up uniformly in x and y 
until at least one dimension fits <tt>size</tt>. Note that everything is
scaled up, including text and node sizes.
<p>
If you're using Postscript, you can just scale up the output by
manually adding a command such as <tt>2 2 scale</tt> where the
Postscript environment is set up.  Make sure to adjust the
<tt>BoundingBox</tt> too if your tools look at this header.
<p>
<A name=Q4 HREF=#Q4>
<B>Q4</A>. How can I join or merge certain edge routes in dot?</B>

<p>
You can try running <tt>dot -Gconcentrate=true</tt> or you can
introduce your own virtual nodes drawn as tiny circles where
you want to split or join edges:

<pre>
digraph G {
  yourvirtualnode [shape=circle,width=.01,height=.01,label=""];
  a -&gt; yourvirtualnode [arrowhead=none]
  yourvirtualnode -&gt; {b;c}
}
</pre>

<P>
<A name=Q4a>
<B>Q. How can I generate graph layouts in PDF?</B>
</A>
<P>
Recent versions of graphviz with the CairoPango based drivers
can generate PDF directly with the <tt>-Tpdf</tt> command line option.
This this first.
<P>
Otherwise, create Postscript output, then use an external converter from
Postscript to PDF.
For example,<BR>
<tt>dot -Tps | epsf2pdf -o file.pdf</tt><br>
Note that URL tags are respected, to allow clickable PDF objects.
<P>
If your intention is to use the figure as PDF in some document preparation 
system, such as pdflatex, it is very important to use -Tps2 rather than
-Tps. In general, if you really want PDF output, that is, you would like
to have a -Tpdf flag, use -Tps2 before converting to PDF. 
<P>
In the diagram below, the shaded nodes will contain bad output.<BR>
<IMG src="pspdf.png">
<P>
<A name=Q4b>
<B>Q. How can I make duplicate nodes?</B>
</A>
<P>
Make unique nodes with duplicate labels.
<pre>
      digraph G {
            node001 [label = "A"];
            node002 [label = "A"];
			node001 -&gt; node002;
	  }
</pre>
<P>
<A name=Q4c>
<B>Q. How can I set a graph or cluster label without its propagating to all sub-clusters?</B>
</A>
<P>
Set the label at the end of the graph (before the closing brace), after all
its contents have been defined. (We admit it seems desirable to define some
special syntax for non-inherited attribute settings.)
<p>
<A name=Q5 HREF=#Q5>
<B>Q5</A>. How can I draw multiple parallel edges in neato?</B>

<p>
This is possible when the <tt>splines</tt> attribute is false, which
is the default. When <tt>splines=true</tt>, we have no good answer but
we are working on it. One trick which is sometimes sufficient is to 
specify multiple colors for the edge. This will a produce set of tightly
parallel splines, each in its specified color. Read about the
<A HREF="info/attrs.html#d:color">color
attribute</A> for more information.

<h2>Clusters</h2>

<A name=Q5a>
<B>Q. How can I create edges between cluster boxes?</B>
</A>
<p>
This only works in Graphviz version 1.7 and higher.
To make edges between clusters, first set the
graph attribute <tt>compound=true</tt>.
Then, you can specify a cluster by name as
a <i>logical head or tail</i> to an edge. This will
cause the edge joining the two nodes to be
clipped to the exterior of the box around the
given cluster.
<p>
For example,
 
<pre>
      digraph G {
        compound=true;
        nodesep=1.0;
        subgraph cluster_A {
          a -&gt; b;
          a -&gt; c;
        }
        subgraph cluster_B {
          d -&gt; e;
          f -&gt; e;
        }
        a -&gt; e [ ltail=cluster_A,
                 lhead=cluster_B ];
      }
</pre>

has an edge going from <tt>cluster_A</tt> to
<tt>cluster_B</tt>. If, instead, you say
 
<pre>
        a -&gt; e [ltail=cluster_A];
</pre>
 
this gives you an edge from <tt>cluster_A</tt> to node
<tt>e</tt>. Or you could just specify
an <tt>lhead</tt> attribute.
 
The program warns if a cluster specified as a
logical node is not defined.
Also, if a cluster is specified as a logical
head for an edge, the real
head must be contained in the cluster, and
the real tail must not be.
A similar check is done for logical tails. In
these cases, the edge
is drawn between the real nodes as usual.
<p>
<A name=Q6 HREF=#Q6>
<B>Q6</A>. Clusters are hard to see.</B>

<P>
Set <tt>bgcolor=grey</tt>
(or some other color)
in the cluster.
<P>
<A name=Q7 HREF=#Q7>
<B>Q7</A>. How can I symmetrize (balance) tree layouts?</B>

<P>
When a tree node has an even number of children, it isn't necessarily
centered above the two middle ones.  If you know the order of the children,
a simple hack is to introduce new, invisible middle nodes to re-balance
the layout. The connecting edges should also be invisible. For example:
<pre>
digraph G {
a -&gt; b0;
xb [label="",width=.1,style=invis]
a -&gt; xb [style=invis];
a -&gt; b1;
{rank=same b0 -&gt;  xb -&gt; b1 [style=invis]}
b0 -&gt; c0;
xc [label="",width=.1,style=invis]
b0 -&gt; xc [style=invis];
b0 -&gt; c1;
{rank=same c0 -&gt;  xc -&gt; c1 [style=invis]}
}
</pre>
This trick really ought to be build into our solver (and made
independent of the order of the children, and available for
layouts other than trees, too).

<H2>Output features</H2>

<A name=Q8 HREF=#Q8>
<B>Q8</A>. How can I get high quality (antialiased) output?</B>

<P>
The easiest thing may be to make the layout in Postscript (option <tt>-Tps</tt>),
then run through <A HREF="http://www.cs.wisc.edu/~ghost/">Ghostview</A> with
antialiasing enabled.  The important command line options are
<tt>-dTextAlphaBits=4 -dGraphicsAlphaBits=4</tt>
(4 is the highest level of antialiasing allowed - see the
<A HREF="http://www.cs.wisc.edu/~ghost/doc/GPL/8.15/Use.htm">Ghostview documentation</A>).
The full command line to render a raster could be something like:
<pre>
gs -q -dNOPAUSE -dBATCH -dTextAlphaBits=4 -dGraphicsAlphaBits=4 -sDEVICE=png16m -sOutputFile=file.png file.ps
</pre>
<P>
On Mac OS X, the <A HREF="http://www.pixelglow.com/graphviz/">pixelglow</A> port
uses Apple's Quartz renderer, which enables antialiasing.  It also provides a beautiful document container for its user interface. (One downside is
that you can't run Pixelglow Graphviz as a web server or other background
process if your Mac has 3D graphics, because Quartz wants to get this resource
to accelerate rendering. Another problem is that as of this writing,
Pixelglow Graphviz hasn't been updated in a long time, maybe mid 2004.)
<P>
On the Linux bleeding edge, Graphviz has an optional plugin to use
the <A HREF="http://www.cairographics.org">cairo</A> back end,
which has antialiased, path-based graphics.  If you want this,
you must install cairo, which is not part of Graphviz.  Cairo is
available in recent versions of Fedora linux, or it can be built
from source.
<P>
<A name=Q9 HREF=#Q9>
<B>Q9</A>. I can only get 11x17 output.</B>

<P>
It's not us!  It's probably your printer setup.  If you don't
believe this, run <tt>dot -Tps</tt> and look at the
<tt>BoundingBox</tt> header.  The coords are in 1/72ths of an inch.
 
<P>
<A name=Q10 HREF=#Q10>
<B>Q10</A>. How do I create special symbols and accents in labels?</B>

<P>
The following solution only works with the
raster drivers that load Truetype or Type1
fonts!  (That means, <tt>-Tgif, -Tpng, -Tjpeg</tt>, and possibly
<tt>-Tbmp</tt> or <tt>-Txbm</tt> if enabled). 
 
Use UTF8 coding, <i>e.g.</i> &amp;#165; for the Yen currency symbol &#165.
Example:
 
<pre>
      graph G {
            yen [label="&amp#165;"]
      }
</pre>
<P>
You can look up other examples in this handy 
<A HREF="http://www.graphviz.org/doc/char.html">
character set reference</A>.
<P>
<A name=Q10b>
<B>Q. More generally, how do I use non-ASCII character sets?</B>
</A>
<P>
The following applies to Graphviz 2.8 and later.  (In older versions
of Graphviz, you can sometimes get away with simply putting
Latin-1 or other UTF-8 characters in the input stream, but the
results are not always correct.)
<P>
<B>Input:</B> the general idea is to find the
<A HREF="http://en.wikipedia.org/wiki/Unicode">Unicode</A>
value for the glyph you want, and enter it within a text
string "...." or HTML-like label <...>.
<P>
For example, the mathematical <it>forall</it> sign (&#8704;) has the value 0x2200.
There are several ways this can be inserted into a file.
One is to write out the ASCII representation: "&amp;#&lt;nnn&gt;;" where &lt;nnn&gt;
is the decimal representation of the value. The decimal value of 0x2200 is 8704,
so the character can be specified as "&amp;#8704;" . Alternatively, Graphviz
accepts UTF-8 encoded input.  In the case of forall, its UTF-8 representation
is 3 bytes whose decimal values are 226 136 128. For convenience, you
would probably enter this using your favorite editor, tuned to your character set
of choice. You can then use the <A HREF="http://www.gnu.org/software/libiconv/#TOCdownloading">
iconv</A> program to map the graph from your character set to UTF-8 or Latin-1.
<P>
We also accept the HTML symbolic names for Latin-1 characters as suggested
<A HREF="#Q10">above</A>.
(Go to http://www.research.att.com/~john/docs/html/index.htm and click
on Special symbols and Entities) For example, the cent sign (unicode
and Latin-1 value decimal 162 can be inserted as
<pre>
&amp;cent;
</pre>
<P>
Note that <b>the graph file must always be a plain text document</b>
not a Word or other rich format file.  Any characters not enclosed in "..."
or <...> must be ordinary ASCII characters. In particular, all of the DOT
keywords such as <tt>digraph</tt> or <tt>subgraph</tt> must be ASCII.
<P>
Because we cannot always guess the encoding, you should set the graph
attribute <tt>charset</tt> to 
<A HREF="http://en.wikipedia.org/wiki/UTF-8">UTF-8</A>,
<A HREF="http://en.wikipedia.org/wiki/Latin-1">Latin1</A>
(alias ISO-8859-1 or ISO-IR-100)
or 
<A HREF="http://en.wikipedia.org/wiki/Big-5">Big-5</A> for
Traditional Chinese.  This can be done in the graph file or on the command line.
For example <tt>charset=Latin1</tt>.
<P>
<B>Output:</B> It is essential that a font which has the glyphs for your
specified characters is available at final rendering time.
The choice of this font depends on the target code generator.
For the gd-based raster generators (PNG, GIF, etc.) you need a
TrueType or Type-1 font file on the machine running the Graphviz program. 
If Graphviz is built with the <tt>fontconfig</tt>
library, it will be used to find the specified font. Otherwise, Graphviz will
look in various default directories for the font. The directories to be
searched include those specified by the <tt>fontpath</tt> attribute,
related environment or shell variables
(see the <a href=http://www.graphviz.org/doc/info/attrs.html#d:fontpath>fontpath</A> entry),
and known system font directories. 
The table
<A HREF="http://www.graphviz.org/doc/char.html">
http://www.graphviz.org/doc/char.html</A>
points out that these glyphs are from the <tt>times.ttf</tt> font.
With fontconfig, it's hard to specify this font.  <tt>Times</tt> usually gets
resolved to Adobe Type1 times, which doesn't have all the glyphs seen on that page.)
<!--- can someone explain whether Cairo differs from libgd here? --->
<P>
For Postscript, the input must be either the ASCII subset of UTF-8
or Latin-1. (We have looked for more general solutions, but it
appears that UTF-8 and Unicode are handled differently for every
kind of font type in Postscript, and we don't have time to hack
this case-by-case.  If someone wants to volunteer to work on this, let us know.)
<P>
For SVG output, we just pass the raw UTF-8 (or other encoding)
straight through to the generated code.
<P>
Non-ASCII characters probably won't ever work in Grappa
or dotty, which have their own back end rendering. 
(Though, Java supports UTF-8, so there's a chance
Grappa also handles raw UTF-8 strings.)
<P>
As you can see, this is a sad state of affairs.
Our plan is to eventually migrate Graphviz to the
<A HREF="http://www.pango.org/">pango</A> text formatting
library, to ameliorate the worst of these complications.
<P>
<A name = Q11>
<B>Q. How do I get font and color changes in record labels or other labels?</B>
</A>
<P>
This is not possible in record shapes. However, you can do this using
<A HREF="info/shapes.html#html">
HTML-like labels</A>. The granularity of changes is still at the cell level,
but by playing with cell spacing and padding, you can get pretty much
the effect you want. The intention is to support arbitrary font changes
within running text in the not-too-distant future.
 
<P>
<A name=Q12 HREF=#Q12>
<B>Q12</A>. In plain format, splines do not touch the nodes (arrowheads are missing).</B>

<P>
Edges are specified as the main spline and, if necessary, arrowheads
which actually abut the node. If the arrowheads are not given, drawing
the edge spline will leave a gap between the edge and the node.
This is a bug which has now solidified into a feature. 
A workaround is to set
       
<pre>
      edge [dir=none]
</pre>
Since the edges have no arrowheads, the spline specification will go
all the way to both nodes. 
<P>
<A name=Q13 HREF=#Q13>
<B>Q13</A>. Record nodes are drawn differently in dot and neato when rankdir=LR.</B>

<P>
It's true.  dot -Grankdir=LR rotates record nodes so that their top level
fields are still listed across levels.  rankdir=LR has no effect in neato.
One workaround is
<A HREF="info/shapes.html#html">
HTML-like records</A> (they don't rotate; the downside is that
you have to write in XML). Another workaround is to enclose
record labels in { } to rotate/unrotate the record contents. See also,
<A HREF="http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnhfact/html/hfactor8_5.asp">How To Avoid Foolish Consistency</A>
by Scott Berkun (Microsoft Corp.)
<P>
<A name=Q14 HREF=#Q14>
<B>Q14</A>. How can I print a big graph on multiple pages?</B>

<P>
The <tt>page</tt> attribute, if set, tells Graphviz to print the
graph as an array of pages of the given size. Thus, the graph
<pre>
digraph G {
  page="8.5,11";
  ...
}
</pre>
will be emitted as 8.5 by 11 inch pages. When printed, the
pages can be tiled to make a drawing of the entire graph.
At present, the feature only works with PostScript output.
<P>
Alternatively, there are various tools and viewers which will take
a large picture and allow you to extract page-size pieces, which can
then be printed.
<P>
<A name=Q15>
<B>Q. When I have a red edge it shows up as a
solid red in PNG and GIF formats, but has a
black border when rendered to JPEG.  </B>
</A>
<P>
This is an artifact of JPEG's lossy
compression algorithm.  JPEG isn't very good
for line drawings.  PNG is bitmap format of
choice.  John Ellson wants to deprecate and
eventually remove the JPEG driver, but North
is reluctant to change anything that people
might already rely on.
<P>
<A name=Q16 HREF=#Q16>
<B>Q16</A>. How can I get custom shapes or images in my graph?</B>
<P>
Please see the
<A HREF="http://www.graphviz.org/Documentation/html/shapehowto.html">
Shape HowTo</A> for some approaches.  There is no easy way to create
custom shapes that work with dot/neato, dotty
(Unix or MS-Windows) and Grappa (the Java
front end), because they don't share any universal back end structure.
We're thinking about it.
<P>
<A name=Q16 HREF=#Q16b>
<B>Q16b</A>. Why don't my custom GIF images appears? What is the meaning of <tt>Warning: No loadimage plugin for "gif:cairo"</tt>?</B>
<P>
Prior to graphviz-2.25.20090911* the 
cairo based renderers couldn't import GIF or JPG. Workarounds, use PNG images. (Possibly, install 
Imagemagick and run "convert shape.gif shape.png". Or try <tt>-Tgif:gd</tt>.)
<P>
<A name=Q17 HREF=#Q17>
<B>Q17. Sometimes in dotty, right mouse click shows the global menu
but none of the items can be selected.</B>
</A>
<P>
Check that the NUMLOCK key is off.  It's a
<A HREF="http://www.research.att.com/~erg/graphviz/bugs/b524.html">
known bug</A>.
<P>
<A name=Q18 HREF=#Q18>
<B>Q18</A>. Why does dotty report a syntax error on a legal dot file?</B>

<P>
Typically this error is reported as:
<pre>
>> graph parser: syntax error near line 14
>> context:  >>>  <<< digraph G {
>> dotty.lefty: giving up on dot
>> dotty.lefty: graph that causes dot
>> dotty.lefty: to fail has been saved in file dottybug.gv
</pre>
Probably there is a command in your shell environment (such as
.alias or .profile) that does output even for non-interactive shells.
When this occurs, those characters go in the pipe to the dot parser
and cause this problem.  An easy check is whether other users have
the same problem.
<P>
<A name=Q20>
<B>Q. How can I get some display feature (such
as bold lines) in dotty?</B>
</A>
<P>
<A NAME="dotty_note">Dotty</A> has not really changed for many years. Therefore, there are
myriad features available in Graphviz which it cannot handle.
In some cases, you can use 
<A HREF="http://www.research.att.com/~john/Grappa/">Grappa</A> 
or <A HREF="http://www.graphviz.org/webdot/">webdot</A> 
for display instead of dotty.  
For example, Grappa has generalized polygons 
(<tt>node [shape=polygon]</tt>) that dotty lacks.
There are additional interactive viewers available. For example, see
<A HREF="http://www.graphviz.org/Resources.php">Graphical Interfaces</A>
and <A HREF="http://www.graphviz.org/About.php">Viewers</A>. If you
are using Mac OS X, the <A HREF="http://www.pixelglow.com/graphviz/">Mac
version</A> of Graphviz has a highly recommended GUI.
<P>
If the display attribute that you need isn't there already, in dotty,
there's probably no easy way to do it except by rolling up
your sleeves and hacking the dotty code (a lefty script) that
interprets and renders graphical attributes.  This is problematic
for the same reason as above: there's no universal low-level driver
layer shared across all the Graphviz tools.  We recently added an
intermediate rendering language to the layout tools, but the
various front ends don't use it yet.  This would be a good project
for someone who wants to get involved here (along with porting
dotty to GTK.)
<P>
<A name=Q21>
<B>Q. How can I get rid of the little circles on
edges ("edge handles") in dotty?</B>
</A>
<P> 
Edit the file dotty.lefty and change the
line that says: 'edgehandles' = 1; to 'edgehandles' = 0;
it's around line 110.
<P>
<A name=Q22>
<B>Q. I already have all the coordinates for the
nodes and edges of my graph and just want to
use dot, neato, or dotty to render it.  How?</B>
</A>
<P>
Put the graph with layout attributes into a dot
file. 

Then run <tt>neato -s -n2</tt>. For example:
<pre>
neato -s -n2 -Tgif file.gv -o file.gif
</pre>
Note that if an edge does not have a <TT>pos</TT> attribute
defined, neato will perform whatever edge routing it would
normally do. All of the usual backend attributes (<TT>size</TT>,
<TT>overlap</TT>, <TT>page</TT>, etc.) are available.
<P>
<A name=Q23>
<B>Q. I already have all the coordinates for the
nodes, and I want dot or neato to route the edges.</B>
</A>
<P>
It's not really too convenient to use dot for this.
It is possible to use neato for this,
running neato -s -n For example:
<pre>
neato -s -n -Tgif file.gv -o file.gif
</pre>
neato will use the node positions, but use its technique
for routing the edges. There are several things to note. First,
the neato edge router is different from dot's. Without the built-in
top-down bias, it doesn't do as good a job of avoiding edge overlaps
and, at present, it doesn't handle spline multi-edges at all. Second, by
default, neato uses straight lines as edges. To get spline routing,
you have to specify -Gsplines=true. And this will only work if none of
the nodes overlap. Since the input graph supplies fixed node positions,
it is the user's task to insure this.
<P>
<A name=Q24>
<B>Q. I already have all the coordinates for the
nodes and edges of my graph and just want to
use dotty to render it.  How?</B>
</A>
<P>
Just run dotty on it. Dotty will use the given pos attributes.
<P>
<A name=Q25 HREF=#Q25>
<B>Q25</A>. Same as above, but I have only node coords, not edges.</B>

<P>
<tt>neato -n</tt> is some help, but neato doesn't handle
spline-based parallel edges. 
<P>
<A name=Q26 HREF=#Q26>
<B>Q26</A>. How can I make client-side image maps?</B>

<P>
Use the -Tcmap command line option (only version 1.8.9 and beyond!)
<P>
<A name=Q27 HREF=#Q27>
<B>Q27</A>. Why aren't my server-side maps being recognized? I've checked the HTML!</B>

<P>
Make sure that your server has map files enabled. For example, if running
apache, check that httpd.conf has a line like the following:
<pre>
AddHandler imap-file map
</pre>
and that it is not commented out!
<P>
<A name=Q28>
<B>Q. I've installed Debian Graphviz and it works just fine on the command line,
but when I execute a Perl/CGI script through Apache, no output is generated.</A>
For example, the code
<tt>
system("/usr/local/bin/dot -Tpng /tmp/tree.gv -o /tmp/tree.png");
</tt>
produces no file <tt>/tmp/tree.png</tt>.</B>
<P>
As best as we can tell, dot dies with no stdout or stderr messages on Debian 
systems when run from an Apache cgi program
with no HOME set. The workaround is to provide a HOME directory in the 
Apache userid's environment.
<P>
Someone has also suggested using the 
<A HREF="http://search.cpan.org/search?query=graphviz&amp;mode=all">
Perl module for Graphviz</A>.
<P>
<A name=Q29 HREF=#Q29>
<B>Q29</A>. How can I get 3D output?</B>

<P>
The Graphviz authors have qualms about the gratuitous use of 3D.
<p>
Nonetheless, dot -Tvrml generates VRML files.  There's no Z coordinate
layout - you specify Z coords yourself in the <tt>z</tt> attribute of nodes,
and the Z coordinates of edges are interpolated.   If someone
contributes a driver for a newer, more useful format (OpenGL Performer
scene graphs? Open Scene Graphs? Java3D programs?) we'd like to try it.
<p>
neato internally supports layouts in higher dimensions through the <tt>dim</tt>
attribute, e.g. <tt>neato -Gdim=7</tt> but there's no way to get the output
unless you invoke neato as a library and inspect ND_pos(n)[i]
where n is a pointer to the relevant node.
This would need some (minor) driver work and a good 7-dimensional viewer. Well,
<tt>dim=3</tt> ought to be possible.

<H2>Problems</H2>
<A name=Q30 HREF=#Q30>
<B>Q30</A>. How can I avoid node overlaps in neato?</B>

<P>
Use the graph attribute <A HREF="info/attrs.html#d:overlap"><tt>overlap</tt></A>.
<P>
<A name=Q31 HREF=#Q31>
<B>Q31</A>. How can I avoid node-edge overlaps in neato?</B>

<P>
Use the <tt>overlap</tt> attribute to leave room among the nodes, then
use <tt>-Gsplines=true</tt>.
<pre>
neato -Goverlap=... -Gsplines=true -Gsep=.1
</pre>
<P>
The <tt>sep</tt> argument is the node-edge separation as
a ratio of a node's bounding box. That is, <tt>sep=.1</tt> means
each node is treated as though it is 1.1 times larger than it is.
The actual value may require some tinkering.
(Don't ask why this isn't just a constant!)  Note that this option really
slows down neato, so should be used sparingly and only
with modest-sized graphs.
<P>
<A name=Q32 HREF=#Q32>
<B>Q32</A>. Neato runs forever on a certain example.</B>

<P>
First, how big is your graph? Neato is a quadratic algorithm, roughly
equivalent to statistical multidimensional scaling. If you
feed it a graph with thousands of nodes and edges, it can easily take
hours or days. The first thing to check is to run <tt>neato -v</tt> to
get a trace of the output. If the numbers you see are generally
getting smaller, the layout is just taking a long time. You can set
certain parameters, such as <tt>epsilon</tt> or <tt>maxiter</tt> to
shorten the layout time, at the expense of layout quality. But if your
graph is big, who's going to notice?
<P>
If you see
the numbers repeating, or fluctuating up and down, then neato is
cycling, especially if your graph is small.
This should never happen by default for versions later than 1.13. If it
does, please report it as a bug.
<P>
If you are using an earlier version of neato, or you used <tt>mode=KK</tt>,
cycling is indeed possible. This cycling is very sensitive to the
initial layout. By using the <tt>start</tt> attribute, for example,
<pre>
neato -Gstart=3
neato -Gstart=rand
</pre>
the cycling will most likely disappear. Or you can employ the parameters used
for large graphs to stop the layout earlier:
<pre>
neato -Gepsilon=.01
neato -Gmaxiter=500
</pre>
<P>
Note that, if you have a large graph, the generation of edges as splines
is a cubic algorithm, so you would do well to avoid using <tt>splines=true</tt>.
(This commment applies to circo, fdp and twopi as well.)
<P>
<A name=Q33 HREF=#Q33>
<B>Q33</A>. Edge label placement in neato is bad.</b>

<p>
Difficult problem.  We're working on it.
If anyone has some general
label placement code (e.g. a simulated annealer based on the Marks et al.
technique in <I>Graphics Gems IV</I>), please get in touch.
<P>
<A name=Q34 HREF=#Q34>
<B>Q34</A>. Dot runs forever on a certain example.</B>

<p>
Try dot -v to observe its progress.
<p>
Note that it's possible to make graphs whose layout or even parsing
is quadratic in the input size. For example, in dot, 

<pre>
digraph G {
    a -&gt; b -&gt; c -&gt; .... -&gt; x -&gt; y -&gt; z
    a -&gt; z
    b -&gt; z
    c -&gt; z
    /* and so on... */
	x -&gt; z
}
</pre>

The total edge length (therefore the layout time) of
this as a ranked graph is quadratic in the number of nodes.


You probably won't encounter the following, but it is also possible
to construct graphs whose parsing takes quadratic time in the number
of attributes, by appending attributes to nodes and edges after the 
graph has been loaded. For example:

<pre>
digraph G {
    /* really big graph goes here...with N+1 nodes */
    n0 -&gt; n1 -&gt; ... -&gt; nN;

    n0 [attr0="whatever",
        attr1="something else",
    /* and so on with many more attributes */
        attrM="something again"]
}
</pre>
When an attribute first appears, each object is visited with possible cost
proportional to the number of previously declared attributes. Thus,
the running time for the above would be <I>cN</I> O(<I>M</I>)
for some constant <I>c</I>. If there is any concern about this, the
graph should specify the attributes first before declaring nodes or
edges. In practice, this problem is neglible.
<P>
<A name=Q34a>
<B>Q. Twopi runs forever on a certain example.</B>
</A>
<p>
Is your graph is large (many thousands of edges),
and did you set <pre>splines=true</pre>?  It takes
a lot of cycles to fit all those splines!
<p>
<A name=Q35>
<B>Q. Neato has unnecessary edge crossings, or has missed an
obvious chance to make a much nicer layout.</B>
</A>
<P>
Neato and all similar virtual physical model algorithms rely
on heuristic solutions of optimization problems. The better
the solution, the longer it takes to find. Unfortunately, it
is also possible for these heuristics to get stuck in local
minima. Also, it is heavily influenced by the initial position
of the nodes. It is quite possible that if you run neato again,
but with a different random seed value,
or more iterations, you'll get a better layout.  For example:
<pre>
neato -Gstart=5 file.gv -Tps -o file.ps
neato -Gepsilon=.0000001 file.gv -Tps -o file.ps
</pre>
<P>
In particular, note that there are no guarantees that neato will produce
a planar layout of a planar graph, or expose all or most of a graph's
symmetries.
<P>
<A name=Q36 HREF=#Q36>
<B>Q36</A>. Webdot doesn't work.</B>

<P>
We assume you're using Apache and have <A HREF="http://www.tcl.tk/">TCL</A> installed.
If you don't, it's probably better to just use the
<A HREF="http://www.graphviz.org/Misc/webdot.pl">
webdot perl script</A>.
<P>
To debug webdot, first test whether <tt>tclsh</tt> can load the
Tcldot shared library.  Try:
<pre>
$ tclsh
% load <b>$prefix</b>/lib/graphviz/libtcldot.so.0
%
</pre>
where <b>$prefix</b> is the installation prefix for graphviz; usually /usr
or /usr/local.
<p>
Then test whether webdot runs from a shell command.  (With webdot we provide
a helper script scaffold.tcl or scaffold.sh that sets up an environment
like the one Apache provides.)  For example
<pre>
$ scaffold.tcl >out.gif
can't read "LIBTCLDOT": no such variable
    while executing
"file mtime $LIBTCLDOT"
    invoked from within
"set t1 [file mtime $LIBTCLDOT]"
    (file "cgi-bin/webdot" line 67)
    invoked from within
"source cgi-bin/webdot
"
    (file "scaffold.tcl" line 22)
</pre>
The above is a strong clue that webdot is not configured properly. 
<P>
Finally, test whether webdot runs as a cgi-bin program.
It may help to examine the cgi-bin environment using a
simple cgi-bin tcl script like:
<pre>
	#!/bin/env tclsh
	puts "Content-type: text/plain"
	puts ""
	foreach e [lsort [array names env]] {puts "$e: $env($e)"}
</pre>
Save this script as .../cgi-bin/test.tcl, make it executable, then
look at: <a href="http://localhost/cgi-bin/test.tcl">http://localhost/cgi-bin/test.tcl</a>
<P>
Also, if you see something like:
<pre>
WebDot Error:

Response Code = 403
</pre>
This usually means that webdot ran succesfully, but was not able
to fetch the remote graph from the URL you gave as an argument.
The reason is probably that your server is behind a firewall that
blocks the webdot server, so it cannot get the graph file.
You can either change firewall permissions, put the graph on a
different server, or install webdot locally so you don't need a
remote server to fetch your graph data.
<P>
It would be nice if someone hacked webdot to take the contents
of a graph as a cgi-bin argument, so it wouldn't need
permission to fetch a graph remotely.
This is left as an exercise for the Open Source Community.
<P>
<A name=Q37 HREF=#Q37>
<B>Q37</A>. I have "Font not found" errors, or text labels missing in webdot.</B>

<P>
Firstly, recent versions of graphviz will use fontconfig if it is available
on your platform.  With fontconfig, this error should not occur, so you
may want to see if an upgrade to graphviz is available, or if a rebuild
will add fontconfig support.
<p>
If fontconfig is not available then graphviz tries to resolve fontnames
to fontpaths itself, and uses DOTFONTPATH (or GDFONTPATH) to indicate where it should look.
<p>
For copyright reasons, Graphviz doesn't come with its own fonts.
On a Windows machine, it knows to search in <tt>C:\Windows\Fonts</tt>.
On a Unix machine, you need to set up a directory that contains
Truetype fonts. You can get a copy of some fonts
<A HREF="http://www.graphviz.org/pub/graphviz/webfonts-1.0-5.noarch.rpm">here</A>.
<P>
The default DOTFONTPATH is:
<pre>
#define DEFAULT_FONTPATH "/usr/X11R6/lib/X11/fonts/TrueType:/usr/X11R6/lib/X11/fonts/truetype:/usr/X11R6/lib/X11/fonts/TTF:/usr/share/fonts/TrueType:/usr/share/fonts/truetype:/usr/openwin/lib/X11/fonts/TrueType:/usr/X11R6/lib/X11/fonts/Type1"
</pre>
If your fonts are somewhere else, then you must set that directory in
the webdot script, or recompile Graphviz with the correct DEFAULT_FONTPATH
(or set <tt>fontpath="/your/font/directory"</tt> in every graph you lay out,
but that's pretty clumsy.)
<P>
<A name=Q38 HREF=#Q38>
<B>Q38</A>. My browser doesn't recognize SVG.</B>

<P>
The correct MIME type for svg images is: <tt>image/svg+xml</tt>   (note "+" not "-").
<P>
SVG is not built into all browsers; you can get
<A HREF="http://www.adobe.com/svg/viewer/install/main.html">plugins</A>
from Adobe for Windows, Linux and some other operating systems.
<A HREF="http://www.mozilla.com/firefox/">
Firefox 1.5</A> has a <A href="http://developer.mozilla.org/en/docs/SVG_in_Firefox_1.5">large subset of SVG</A> and renders graphviz -Tsvg output
though until graphviz 2.8, the fonts may be too large (thanks for
Phil Colbourne at the RailCorp of New South Wales for this advice).
<P>
For help with embedding SVG in HTML pages, see 
<A HREF="http://www.graphviz.org/webdot/svgembed.html">here</A>.
<P>
There are several good standalone viewers and editors for SVG.
We like <A HREF="http://www.inkscape.org">inkscape</A>.
<A HREF="http://www.gnome.org/projects/evince/">evince</A>
is the standard Gnome document viewer that handles SVG, at least
since version 0.5 (though Phil C. reports output is blurred)
(see also <A HREF="">eog</A> (Eye of Gnome)).
Commercial tools like Adobe Illustrator and Microsoft Visio
can import SVG (the better to deal with your content, my dear!)
If you are using an older (less bloated) Unix system, you
may find tools like <A HREF="http://xml.apache.org/batik/">Batik</A>
(an SVG renderer in Java) or <A HREF="http://www.sodipodi.com">sodipodi</A>
useful, though it seems they are no longer very actively maintained.
sodipodi is faster but both make sharp images - isn't that the
beauty of path-based graphics?
<P>
<A name=Q39>
<B>Q39. libexpat is reported as containing a virus or as a security hole.
Is this a real problem?</B>
</A>
<P>
No, this is a false positive reported by various security software.
See <A HREF="http://www.pcreview.co.uk/forums/thread-1689630.php">http://www.pcreview.co.uk/forums/thread-1689630.php</A> or
<A HREF="http://spywareblog.com/index.php/2004/11/24/is_libexpat_dll_spyware">http://spywareblog.com/index.php/2004/11/24/is_libexpat_dll_spyware</A>.
<P>
<A name=Q40 HREF=#Q40>
<B>Q40</A>. What is the coordinate transformation between the graph bb and a .png image?</B>
<OL>
<LI>
The bb is expanded by 4 graph-units in all directions (pad) to allow for finite line widths.
<LI>
Then it is zoomed and/or rotated according to -Gviewport, -Gsize, -Glandscape, -Gorientation options.
At the default scaling of 1:1, one graph unit = 1 point (1/72 inch).
<LI>
Then it is paginated, if requested by -Gpage and if the output format supports it.  Not the -Tpng renderer, yet.
<LI>
Then a margin is added, -Gmargin, in absolute units (inches).
The top/bottom margin can be set independently of the left/right margin.
<LI>
Then it is converted to device units, according to -Gdpi,
or a dpi value that is given by the output device,
or a default that is provided by each render.
There are separate dpi values for x and y to allow for non-square pixels.
Some renderers invert the Y axis and need an offset to place the
origin in the top left corner.
The default dpi for -Tpng is 96dpi (approximating the resolution
of most computer monitors) so this is where the scaling by 96/72 (4/3)
comes from.
</OL>
<P>
At the renderer api, plugins have a choice of coordinate representation:
<UL>
<LI>
coordinates in graph-units, and composite transformation data consisting
of: scaling, rotation, and translation.  (used by svg, cairo, ps, renderers)
<LI>
coordinates pre-transformed into device units. 
</UL>
<P>
<A name=Q41 HREF=#Q41>
<B>Q41</A>. File associations are broken in Mac OSX.  Clicking on a <tt>dot</tt> file doesn't open Graphviz.</B>
<p>
The immediate fix is to rebuild the Launch Services database like this:
<p>
1. 	Trash all other versions of Graphviz.app on your system, except for the just installed one. You can use either of these command lines to find it:
<p>
<pre>locate Graphviz.app</pre>
<p>
or
<p>
<pre>find / -name "Graphviz.app"</pre>
<p>
2.	Run the following command line:
<p>
<pre>/System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/LaunchServices.framework/Versions/A/Support/lsregister -kill -r / </pre>
<p>
or
<p>
<pre>/System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/LaunchServices.framework/Versions/A/Support/lsregister -kill -r /Applications</pre>
<p>
which deletes the Launch Services database and rebuilds it from existing apps. You may need to sudo to do this.
<p>
3.	Verify that the Graphviz.app can now open .gv files and Microsoft Word can still open its own .gv files.
<p>
One artifact of this will be that Microsoft .gv files may appear with the Graphviz document icon. Unfortunately there doesn't seem any a priori way of getting the system to determine whether an arbitrary .gv file belongs to Word or Graphviz -- you can choose which application to open with by right-clicking or control-clicking on the document icon and choosing the app.
<p>
As for why the Launch Services database doesn't automatically register Graphviz,
we're not entirely sure but suspect this only happens if both conditions
hold true:
<p>
A.	The user had installed Microsoft Word.<br>
B.	There is also another version of Graphviz.app present in the system. (Possibly the previous version 1.13 released by Pixelglow Software)<br>
<A name=Q42 HREF=#Q42><B>Q41</A>. What do all these plugin libraries do?</B>
<p>
<ul>
	<li><b>lasi</b> - Adds support for UTF8 characters, beyond ASCII, in postScript output. This table provides a feture comparison of the various PosScript renderers:
	<table>
		<tr>
			<th></th>
			<th>UTF8</th>
			<th>hyperlinks</th>
			<th>human readable PostScript</th>
		</tr>
		<tr>
			<th>-Tps:core</th><td>no</td><td>yes</td><td>++</td>
		</tr>
		<tr>
			<th>-Tps:lasi</th><td>yes</td><td>yes</td><td>+</td>
		</tr>
		<tr>
			<th>-Tps:cairo</th><td>yes</td><td>no</td><td>--</td>
		</tr>
	</table>
	<li><b>gs</b> - Provides support for usershapes in PostScript that can be embedded in all output formats.  It interprets the format and renders to a cairo surface.  Requires a recent version of ghostscript.  (Not needed for PostScript in PostScript) 
	<li><b>rsvg</b> - Provides support for usershapes in SVG that can be embedded in all output formats.  It interprets the format and renders to a cairo surface.  (Not needed for SVG in SVG)
	<li><b>glitz</b> - OpenGL output.   But this may not be the right way to dot it, and my glitz plugin is unfinished.  Not useful at this time.
	<li><b>ming</b> - Flash output.  Was sort of working at one point, not now.  Needs development.  Might be interesting opportunities for a dynamic graph output.  Not useful at this time.
</ul>


</BODY>
</HTML>