No...
This source code save as xparam3.prg and recompile it. Look to err file.

#define INP 
#define REF 
#define OUT 
#define CHNG 

PROCEDURE test(INP REF OUT CHNG luPar1, REF luPar2)

Result:

PROCEDURE test( REF  CHNG luPar1,  luPar2)
Error in line 7: Syntax error.

Why don't replace constants REF and CHNG? But constants INP and OUT are replaced.

MartinJ

>Are they keywords or system variables.?
>
>>Run this example:
>>

>>#define INP
>>#define REF
>>#define OUT
>>
>>? INP REF OUT && Variable 'REF' is not found.
>>? INP REF     && Variable 'REF' is not found.
>>? INP
>>
>>? INP OUT REF && Variable 'OUT' is not found.
>>? INP OUT     && Variable 'OUT' is not found.
>>

>>
>>
>>Why preprocesor ignoring each second constant at compiling?
>>
>>MartinJ