zOs/REXX.O13/@1

say '_' symbol('_') _
_ = 'v=_'
say '_' symbol('_') _
say 'abc_efg' symbol('abc_efg') abc_efg
abc_efg = 'v=abc_efg'
say 'abc_efg' symbol('abc_efg') abc_efg
say '_123' symbol('_123') _123
_123 = 'v=_123'
say '_123' symbol('_123') _123
say '_abc_123_' symbol('_abc_123_') _abc_123_
_abc_123_ = 'v=_abc_123_'
say '_abc_123_' symbol('_abc_123_') _abc_123_
say 1_ 1a 'but are no variables |'
if 0 then
    1_=1a
drop _ abc_efg _123 _abc_123_
say 'm._' symbol('m._') m._
m._ = 'v=m._'
say 'm._' symbol('m._') m._
say 'm.abc_efg' symbol('m.abc_efg') m.abc_efg
m.abc_efg = 'v=m.abc_efg'
say 'm.abc_efg' symbol('m.abc_efg') m.abc_efg
say 'm._123' symbol('m._123') m._123
m._123 = 'v=m._123'
say 'm._123' symbol('m._123') m._123
say 'm._abc._123_' symbol('m._abc_123_') m._abc_123_
m._abc_123_ = 'v=m._abc_123_'
say 'm._abc_123_' symbol('m._abc_123_') m._abc_123_
a = vPut()