Matchcode objects are being replaced by search helps. This is good as search helps are easy to create. However, it has caused some confusion on how best to add search helps to a selection field.
The trick that I found is to keep your newly created search helps to a 4-character name. The Matchcode object name has this old 4-character limit. This trick is not documented anywhere in the system but it has been a great time saver for me. You can expand this concept by finding existing SAP search helps that are more than 4-characters, copy them to a 4-character name and presto, you have a new matchcode object available for use.
PARAMETERS: p_org LIKE t527x-orgeh MATCHCODE OBJECT zorg.