You can use the FIELD directive with an operand of 0 to label a location within a structure. The location is labeled, but the location counter is not incremented.

The size of the data structure defined in Example 2.19 depends on the values of MaxStrLen and ArrayLen. If these values are too large, the structure overruns the end of available memory.

Example 2.19 uses:

An ASSERT directive checks that the end of the data structure does not overrun the available memory.

StartOfData     EQU     0x1000
EndOfData       EQU     0x2000
                MAP     StartOfData
Integer         FIELD   4
Integer2        FIELD   4
String          FIELD   MaxStrLen
Array           FIELD   ArrayLen*8
BitMask         FIELD   4
EndOfUsedData   FIELD   0
                ASSERT  EndOfUsedData <= EndOfData