ValueLength can be used to specify a restriction on the length of the value of an Element. It is not mandatory for this information to be included in the Elements Register – it can be explained in the enty’s defining document instead (indeed, for complicated restrictions this might be the only practical solution).
ValueLength must only be given for an Element if the length restriction goes beyond the restrictions already imposed by its
Type. For example: if the
Type is “UInt8”,
ValueLength must not be set to “1 byte” as that is redundant information.
ValueLength must specify the units in which the length restriction is expressed.
Note that currently (May 2017) the Elements Register contains a lot of historical data in the
ValueLength field and this is neither entirely accurate nor consistent with the guidelines given above.