All Mappings have this attribute.

If a CmpMap’ s component Mappings are joined in series, then its Nin attribute is equal to the Nin attribute of the first component (or to the Nout attribute of the second component if the the CmpMap’ s Invert attribute is non-zero).

If a CmpMap’ s component Mappings are joined in parallel, then its Nin attribute is given by the sum of the Nin attributes of each component (or to the sum of their Nout attributes if the CmpMap’ s Invert attribute is non-zero).

The Nin attribute for a Frame is always equal to the number of Frame axes (Naxes attribute).

The Nin attribute of a FrameSet is equal to the number of axes (Naxes attribute) of its base Frame (as specified by the FrameSet’ s Base attribute). The Nin attribute value may therefore change if a new base Frame is selected.