Workitem customization - Best Practices??

I'm looking for advice on workitem customization best practices and what to do to "future proof" my changes.

For example, what should I use as a naming convention to avoid potential collisions with updates to the out of box definitions in future upgrades?

I've copied and tweaked the default editor presentation (com.ibm.team.workitem.editor.default) to create a custom presentation for Defect work items, so that I can show different attributes for Severity and Priority than Tasks, which uses the same default editor. Initially I duplicated the editor and called it com.ibm.team.workitem.editor.defect, but realized this could easily be used as the name for a future standard defect editor... so would my custom editor get lost? Is there a good convention for naming the new items I create for my customized editors and enumerations?

I came across a few good articles, but can't find the "Best Practices" Tech Note referenced in Work Item Customization in Rational Team Concert

http://jazz.net/library/article/130 - Work Item Editor Presentations

http://jazz.net/library/article/129 - Work Item Customization in Rational Team Concert ... "Safe customizations" are customizations that either add new elements (e.g. work item types) or only change UI related features like display names or editor layouts. The Tech Note "Work Item Customization - Best Practices" explains in more detail how to customize in a safe way.