PROCEDURE.md Requirements changes (#110)

PROCEDURE.md

@@ -4,9 +4,14 @@ DIP submission is open to anyone aiming to improve the D programming language an
 
 This document outlines the DIP process from beginning to end. The process is divided into a sequence of stages. Each stage establishes the specific responsibilities of all relevant parties. The details outlined here are subject to change at any time, and the DIP Manager or the Language Maintainers may allow for exceptions which waive requirements or responsibilities at their discretion.
 
-## Requirements
+## When to Write a DIP
 
-In general, most proposals to enhance the language or to make changes to existing features or syntax will require a DIP. Changes that also affect the compiler output will also usually require a DIP. Even seemingly innocuous changes can have an impact that is not immediately obvious. Anyone considering a serious proposal who isn't sure if a DIP will be required can first make an exploratory post in the D [General discussion forum](https://forum.dlang.org/group/general), but the rule of thumb should be, "When in doubt, write a DIP."
+The following are good indicators that a change warrants a DIP:
+
+* Changes to the language itself, such as syntax/semantics
+* Changes to the functional behavior of code generated by the compiler
+
+Be sure to consider the full impact of any change when deciding if it warrants a DIP. Even seemingly innocuous changes can have an impact that is not immediately obvious. Anyone considering a serious proposal who isn't sure if a DIP will be required can make an exploratory post in the D [General discussion forum](https://forum.dlang.org/group/general), but the rule of thumb should be, "When in doubt, write a DIP."
 
 ## Process