FOLIO's reference data, which we are not using, suggests that these should include "Uniform title" (aka 130, 240, or 730) and the options listed for the 2nd indicator of 246...

• No type specified
• Portion of title
• Parallel title
• Distinctive title
• Other title
• Cover title
• Added title page title
• Caption title
• Running title
• Spine title

...but I think that it would be good to add options that are relevant to other title fields (210, 222, 242, 243, 247, or 740):

• Abbreviated title
• Abbreviated key title
• Collective uniform title
  
• Former title
• Key title
• Translation of title
• Uncontrolled related/analytical title 

All of the above have been added to the alternativeTitleTypes db table via API using /opt/folio/api/POST/alternativeTitleTypes.pl - 6/20/20