Syntax:     BASENAME(string, [suffix])

Defn: A CI evaluator function that returns the base portion
of an MPE or POSIX filename, minus directory or group
and account names. If the suffix is specified then
it is removed from the base name if found.

Type: String

Example: basename('a.b.c')
Result: A
Example: basename('/a/b/c')
Result: c
Example: basename('/')
Result: /
Example: basename('*feq')
Result: *FEQ
Example: basename('$null')
Result: $NULL
Example: basename('/a/b.c', '.c')
Result: b