-- System variable: values Initial value:
values is a list of all bound user variables (not Maxima options or switches). The list comprises symbols bound by
If the value of a variable is removed with the commands
remvalue the variable is deleted from
functions for a list of user defined functions.
values shows the symbols
c, but not
d, it is not bound to a value, and not the user function
f. The values are removed from the variables.
values is the empty list.
(%i1) [a:99, b::a-90, c:a-b, d, f(x):= x^2]; 2 (%o1) [99, 9, 90, d, f(x) := x ] (%i2) values; (%o2) [a, b, c] (%i3) [kill(a), remove(b,value), remvalue(c)]; (%o3) [done, done, [c]] (%i4) values; (%o4) 
There are also some inexact matches for
?? values to see them.
(%o1) true (%i2)