Abbreviation of the directive >> IF constant-conditional-expression

The ">>IF constant-conditional-expression" directive could support a simplified expression:

>>IF compilation-variable-name

- this expression would be true if: (compile-variable-name is defined) AND (its value is equal to B'1', or an integer value other than 0, or a non-empty alphanumeric literal or a alphanumeric literal other than SPACE)

- this expression would be false if: (compilation-variable-name is not defined) OR (its value is equal to B'0', or the integer value 0, or an empty alphanumeric literal, or a alphanumeric literal SPACE)

Currently, the expression ">> IF compile-variable-name is defined" is true regardless of the compile-variable-name value (even for the value B'0'), and test on an undefined compile-variable-name triggers a message "IGYLI0245-E "compilation-variable-name" was not defined as a variable compilation. A value of 1 was assumed for the variable".

This proposal can also apply to format 2 of the ">> EVALUATE" directive:

>> EVALUATE TRUE
>> WHEN compilation-variable-name

The assignment of the default value B'1' to an undefined compilation-variable-name does not seem to be a good choice because it implicitly implies the inclusion of a text conditioned by this compilation-variable-name. The default value of an undefined compilation-variable-name should be B'0', which would partially achieve the result described above.