When the MMC or LMC modifying symbol is not shown in the feature control frame, it is understood that RFS applies.

MMC

Maximum Material Condition, a concept in tolerance specifications indicating the limit state where a part contains the maximum amount of material within its tolerance limits.

LMC

Least Material Condition, the condition of a part where it contains the minimum amount of material yet still meets its dimensional specification, often related to tolerances in manufacturing.

RFS

Regardless of Feature Size; a condition where the tolerance or location of part features is not affected by the feature size.