Hi,

The SYSP keyword dates back over 20 years and the Convert To feature in the Field Data Editor is a relatively new tool (about 2017-2018).  So the SYSP keyword itself would never support this type of functionality.  When the Convert To was added to the FDE, the equivalent keyword was not added to the ZPL.

The 2 options you have for programmatically converting to different field types:

• Use the ZOS-API with the TheSystem.SystemData.Fields.ConvertToFieldType() method
• Staying in the ZPL, use the Merit Function Editor (OPEV function) to get the appropriate “converted” ray values and then simply loop through the FDE to manually change the field values

Since the field type conversion can be a little tricky, especially if you're trying to make it robust between all the different types of field definitions, I would recommend using the ZOS-API but you could create the equivalent functionality via the ZPL as well.