Programmer-generated warning.
WARN[{string | expression}[,{string | expression}]...]
The WARN directive causes a warning message to be output by the Assembler. The total warning count is incremented as with any other warning. The WARN directive is normally used in conjunction with conditional assembly directives for exceptional condition checking. The assembly proceeds normally after the warning has been printed. An arbitrary number of strings and expressions, in any order but separated by commas with no intervening white space, can be optionally specified to describe the nature of the generated warning.
A label is not allowed with this directive.
WARN 'invalid parameter'