/usr/share/afterstep/start/3_run is in afterstep-data 2.2.12-6.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 | Exec "Run ..." ASRun --myname "Run command using AfterStep" &
SmallMiniPixmap "normal/Run"
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