I would suggest
#!/bin/ksh
and that's it. Heavyweight block comments for shell scripts? I get the willies.
Suggestions:
Documentation should be data or code, not comments. At least a usage()
function. Have a look at how ksh and the other AST tools document themselves with --man options on every command. (Can't link because the web site is down.)
Declare local variables with typeset
. That's what it's for. No need for nasty underscores.