SYMBOL(name)

The argument is interpreted as a symbol (or a number); it is uppercased,
and if it is a compound symbol, any simple symbol components of the tail
are substituted in as with the VALUE function. The result is the three
character string "BAD", indicating that the name is not a valid symbol,
"VAR", indicating that the name is a variable (i.e. a symbol which has
been assigned a value), or "LIT", indicating that the name is either a
constant symbol or a symbol without a value.  For example, the program:
   b='*'; a.b=5
   say symbol('a') symbol('b') symbol('a.B') symbol(A.b)
   say symbol('a.*') symbol('b.a') symbol('b.*')
would say "LIT VAR VAR LIT" and "BAD LIT BAD".