To submit a proposal for the UML, a company had to be a tool vendor engaged in the delivery of tools that would implement the standard. The following is a partial list of more than 60 participants.

1. Hewlett-Packard Company
2. IBM Corporation
3. ICON Computing
4. i-Logix
5. IntelliCorp
6. MCI Systemhouse Corporation
7. Microsoft Corporation
8. ObjecTime Limited
9. Oracle Corporation
10. Platinum Technology, Inc.
11. Ptech Inc
12. Rational Software Corporation
13. Reich Technologies
14. Softeam
15. Sterling Software
16. Taskon A/S
17. Unisys Corporation