"direction (i.e. converting input coordinates into output coordinates). If this attribute is non-zero, the forward transformation is available. Otherwise, it is not.
’s base Frame and its current Frame (as specified by the Base and Current attributes). This value is given by the boolean AND of the TranForward values which apply to each of the individual sub-Mappings required to perform this conversion. The TranForward attribute value for a FrameSet may therefore change if a new Base or Current Frame is selected.
An error will result if a Mapping with a TranForward value of zero is used to transform coordinates in the forward direction.