In MS Project you have the WBS code which can be customized.  Go to help for the keystrokes and Project --> WBS to customize.  You also might consider using the unique identifier column.  This is essentially the order the tasks were entered and will never change once the system assigns it.  WBS will be renumbered unless you turn off the feature but it can be customized to automatically assign values you request.

For more tips and tricks using MS Project, go to my website at www.lehnertcs.com.  

I do not use WBS to organize and identify my activities, I don't even use it at all unless forced to do so as a contract requirement. I am looking for a way to organize by other codes and use also my activities ID to sort in a sequential order. A substitute to controlling activities ID is not what I am looking, especially when required to use standardized WBS coding. No other cpm software does not confuse, merge, or substitute one with the other.

Unique identifier does not  provides the control we are used to. It is common practice under other software to assign your initial schedule activities ID with ID numbers 10 units apart. If you are in need to add activities you can use numbers in between, if not enough you can use decimal number or suffix.

Consistency in activity ID is crucial specially when comparing different versions of the schedule keeping your baselines/target under a separate file a more powerful method than just a few additional fields in the same file.

Only if you know the other software you would understand the power of controlling your activities ID while being able to compare changes in updates adding activities ID and not losing track of your activities and so on. This is something all other software can do.

Thanks for your effort but after analyzing if another field would do it I found it won't. I already gave up  MS Project as an alternative.
 

No other cpm software confuse, merge, or substitute one with the other.