#1403 Parsing error with if-keyword statement

[Rony G. Flatscher]

While experimenting with using the variable "if" as the expression in an if-keyword statement, the following code works as expected:

if=1
if if then say "if=1"

whereas the following code (variable "then" as the expression) causes an error "35.929: Missing expression in logical expression list.":

  then=1
  if then then say "then=1"

[Rick McGuire]

This is the correct result. IF is not a sub-keyword of the IF instruction, so using that as a variable name in the test expression has no effect. THEN is a sub-keyword of the instruction and acts as the expression terminator.