Add new time units for DateFormula Datatype

Hi all… I am new to NAV programming and I have a question about DateFormula Datatype:

Is there any way to add new time units (besides D,W,M,Y…) for DateFormula input? For example, I can type 1T (1 trip) or something like 3M+1T,14D+2T… in a field with DateFormula data type. Normally, a DateFormula field only accepts values such as: 8M, 1Y, 1M+8D,…

If it is impossible to customize time units for DateFormula type, can I change the data type of the field to Code or Text, then write some C/AL code to make it accept the values as I said above (with the added time units ‘T’) and the CALCDATE function still understands? I mean using the Code or Text type as substitute for DateFormula type so that I can add new time units.