For an edit buffer loaded from or saved to a file, the Compile Check Syntax option of the Procedure Editor determines what syntax it must contain based on the filename extension. A class (.cls) file must contain CLASS or INTERFACE syntax, or the compiler generates a syntax error when checking the syntax. Any other type of file must not contain CLASS or INTERFACE syntax, or the compiler generates a syntax error when checking the syntax. For an already loaded or saved edit buffer, you do not have to save changes again in order to check syntax.

For an untitled edit buffer, the Procedure Editor determines if the edit buffer contains CLASS or INTERFACE syntax and checks the syntax accordingly. Once you save the untitled edit buffer to a file, the Procedure Editor checks syntax as a loaded or saved edit buffer according to the filename extension.