P-Code compatibility

P-Code incompatibility may be introduced from version to version.

As a general rule, when upgrading to a feature release version like 2.40 to 2.50 or 2.51 to 2.52, you must recompile all your .4gl modules and .per form files. Recompilation is not required when upgrading to a new bug fix release like 2.50.01 to 2.50.02.