C3D files are composed of a number of 512-byte blocks of information that contain the individual sections and records within the C3D file. All C3D files contain three or more sections, each section being comprised of at least one 512-byte block. Within the sections of the C3D file, information is stored in records. All C3D files contain a header record (i.e. the header section), parameter records stored within the parameter section, and data records (3D and/or analog) stored within the data section.
It is worth mentioning at this point that, in deference to the original Fortran environment used to create most C3D applications during the early years, this manual describes C3D file as being composed of a series of 512-byte blocks of information. Programmers often prefer to think of these blocks in terms of their original description within Fortran as 512-byte “records” that translated directly to the physical disk sector storage locations that set physical limits on the storage of data.
In today’s programming environment, this 512-byte constraint is largely eliminated. Its only legacy within the C3D format is that all data or parameter sections start on multiples of 512 bytes. This documentation consistently refers to these 512-byte units of information as blocks rather than the traditional “record” thus freeing the term record to be used to describe individual units of information such as parameters and data samples.
This is more in keeping with the view that the C3D file is a collection of information and data – thus freeing us to discuss parameter records, point records and analog records as items of information that are stored within different sections in the C3D file.