It is to check in which ArchiCAD version the object is running. This is helpful for shipping around some version specific problems or to keep an object downward compatible. Checking if the object is running inside ArchiCAD at all or in the web control could be necessary too.

GDL = REQ("GDL_Version") !»» Request GDL version

IF GDL>=1.278 THEN PRINT "ArchiCAD 7.0 / SE 2003"
IF GDL>=1.279 THEN PRINT "ArchiCAD 8.0 V1"
IF GDL>=1.317 THEN PRINT "ArchiCAD 8.0 V2/V3"
IF GDL>=1.331 THEN PRINT "ArchiCAD 8.1 / SE 2006"
IF GDL>=1.412 THEN PRINT "ArchiCAD 9.0"
IF GDL>=1.516 THEN PRINT "ArchiCAD 10.0"
IF GDL>=1.556 THEN PRINT "ArchiCAD 11.0"
IF GDL>=1.564 THEN PRINT "ArchiCAD 12.0"
IF GDL>=1.604 THEN PRINT "ArchiCAD 13.0"
IF GDL>=1.605 THEN PRINT "ArchiCAD 14.0"
IF GDL>=1.606 THEN PRINT "ArchiCAD 15.0+"