The $QSUBSCRIPT function returns a component of a variable name.
The format of the $QSUBSCRIPT function is:
$QS[UBSCRIPT](namevalue, intexpr)
The namevalue has the form of an evaluated subscripted or unsubscripted global or local variable name.
The intexpr selects the component of the name as follows:
-2 is reserved but may be "error",
-1 for environment,
0 for the unsubscripted name,
1 for the first subscript,
2 for the second subscript, and so on.
If the second argument selects a component that is not part of the specified name, $QSUBSCRIPT() returns an empty string ("").