Add several Fields at Operations level in Maintenance Order

Hello SAP Gurus,

In my PM order, I want to add more than 12 fields (CHAR) on the tab "Enhancement",.at Operations level...

I have searched the forums and the 2 main solutions found don't solve my issue:

- Exit IWO10018: it works ONLY for Maintenance Order Header.

- The customizing transaction OILJ: it allows to add ONLY 12 fields with fixed data category and lengh (4xCHAR, 2xQUAN, 2xUN, 2xCURR, 2xDATS)

Since I need a few more fields with different data category, at operation level, can you please suggest any other possibilities? thanks!