No worries, but that's not how you should look at it
In the previous example, if you Compile/Run YourForm.pb, it is the main file and #PB_Compiler_IsMainFile = 1
And if you compil MainFile.pb, YourForm.pb is not the the main file and #PB_Compiler_IsMainFile = 0. The code in YourForm.pb after CompilerIf #PB_Compiler_IsMainFile is not taken into account by the compiler in this case, it is not the the main file.

