If you want to create new text ID that will be available in SO10 transaction, then follow these easy steps below.

1. Go to TCode SE75
2. Select “Text Objects and IDs” and click on the “Change” button (you need sufficient rights/authorizations for maintenance, otherwise you will be allowed to read only)
3. In the list that is displayed, navigate to OBJECT = TEXT and double click on it
4. Now you can maintain existing IDs or add a new one.

Once you add new ID using the steps above, you should be able to see it (select it) in SO10 as your text ID.