I like your proposal: it seems move active. I am in the process of updating my program, so I will support both formats. The old format @UF=RD specifies the result of moving into the BLD reading orientation of red up yellow front (for Western colored cubes). The alternative active motion format you like will now read @BL=UF, which also specifies red up yellow front. The "=" in computer science in some languages is ":=" and is pronounced 'becomes' -- it should be clear either way.
For programming purposes, I will ignore any request that does not have "UF" on either or both sides of the "equation". Of course, if "UF" is on both sides, the result is a no-op (no operation).