The POINT:DESCRIPTIONS parameter is a character data array that usually consists of a short description of each 3D data point referenced by the POINT:LABELS parameter.  There should always be a one to one relationship between the number of LABELS and the number of DESCRIPTIONS.  By convention, these entries usually contain upper and lower case ASCII characters and are typically 32 characters in length but may be up to 127 characters long in a signed C3D file or 255 characters in an unsigned C3D file.

Although it is not strictly required, it is good practice to include a DESCRIPTIONS parameter for each point with a LABELS entry.  Since this is an array of character strings, the comments in the LABELS parameter description regarding the maximum number of array entries also apply to this parameter.  Signed C3D files cannot contain more than 127 DESCRIPTIONS while unsigned C3D files may contain up to 255 DESCRIPTIONS.

This parameter exists to provide documentation about each of the individual 3D POINT:LABELS, which are generally short abbreviations of anatomical or other “landmarks” such as LASI, RKNE etc.  These names generally have longer POINT:DESCRIPTIONS such as Left ASIS Marker and Right Knee Marker.