Hi, Martin,
I'm Judy, a Revit specialist, and I'll be glad to help you out with this question. In the 2016 version of Revit products, it's now possible to create an alphanumeric sequence of revisions, so you no longer need to use the Issued To and Issued By columns as a workaound.
Here's how:
1. In the Sheet Issues/Revisions dialog, click Alphanumeric under Numbering at the right.
2. Type in the revision sequence you want to use exactly as you described it (P1,P2,T1,T2,C1,C2 etc.) Note that once all the values are used, it will repeat again with doubled values, so you'll see P1P1 after C2, so just add more values to the sequence where and when they are needed. (You don't need a prefix or suffix in this case.)
3. Click OK.
4. In the Sheet Issues/Revisions dialog, set the numbering to Alphanumberic, and click Add. Revisions will be created in the order in which you listed them in the previous step. See the image below.
Hope this answers your question! If so, please click the "Accept as Solution" button. This helps everyone find answers more quickly!
Let me know if you have any other questions.
Cheers,
Judy Staicer
