/usr/share/a2ps/encoding/encoding.map is in a2ps 1:4.14-1.3.
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  | # -*- ksh -*-
#
# This file is part of a2ps.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3, or (at your option)
# any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; see the file COPYING.  If not, write to
# the Free Software Foundation, 59 Temple Place - Suite 330,
# Boston, MA 02111-1307, USA.
#
#
# This file defines the rules used by a2ps to select an encoding.
#
# The format of each line is:
#
# <alias> <encoding>
#	In which case whenever <alias> is requested, a2ps uses the
#	<encoding>.  Matching to <alias> is case insensitive, hence <alias>
#	and <key> must be lower case in this file.
#
# *** <path>
#	In which case a encoding.map is included at this point.
#	This may be the case if you define a personal extension
#	of the system's encoding.map
#
########################################################################
# The ASCII encoding
########################################################################
ascii			ascii
us-ascii		ascii
########################################################################
# The ISO encodings
########################################################################
latin1			iso1
iso1			iso1
iso-8859-1		iso1
latin2			iso2
iso2			iso2
iso-8859-2		iso2
latin3			iso3
iso3			iso3
iso-8859-3		iso3
latin4			iso4
iso4			iso4
iso-8859-4		iso4
iso5			iso5
iso-8859-5		iso5
iso7			iso7
iso-8859-7		iso7
# The following lines _are_not_an_error_.
# This is the right correspondance between ISO-8859 names
# and the Latin n nick name.
latin5			iso9
iso9			iso9
iso-8859-9		iso9
latin6			iso10
iso10			iso10
iso-8859-10		iso10
latin7			iso13
iso13			iso13
iso-8859-13		iso13
# This one is nicknamed latin0 too
iso15			iso15
latin9			iso15
latin0			iso15
iso-8859-15		iso15
########################################################################
# Other encodings
########################################################################
koi8-r			koi8
koi8r			koi8
koi8			koi8
koi			koi8
euc-jp			euc-jp
eucjp			euc-jp
japanese		euc-jp
ja			euc-jp
jp			euc-jp
########################################################################
# Some architectures specific char sets
########################################################################
# MicroSoft's CP 1250
ms-cp1250		ms-cp1250
cp1250			ms-cp1250
1250			ms-cp1250
cep			ms-cp1250
# MicroSoft's CP 1251
ms-cp1251		ms-cp1251
cp1251			ms-cp1251
windows-1251		ms-cp1251
# IBM PC
ibm-cp850		ibm-cp850
cp850			ibm-cp850
850			ibm-cp850
pc			ibm-cp850
ibmpc			ibm-cp850
# PC graphic
ibm-cp437		ibm-cp437
cp437			ibm-cp437
437			ibm-cp437
pcg			ibm-cp437
# Hewlett Packard
hp			hp
hp8			hp
# Apple' Macintosh
mac			mac
macintosh		mac
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