/usr/bin/save2aecg is in biosig-tools 1.3.0-2+b2.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
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#!/bin/sh #conversion into HL7aECG data format save2gdf -f=HL7 $1 $2 $3 $4 $5 $6 $7