The data values (pixels) of a Bulk Data Frame are stored by default as floating point (real) numbers using 32 bits per pixel. However, your application may use bytes (8 bits), unsigned short integers (16 bits), integers (32 bits) or double precision (64 bits) per pixel as well.
Bulk Data Frames and their associated Descriptors are stored together as a normal (unformatted) file on disk. We refer to this file as a Bulk Data Frame as well. The internal format of this file is not described in this document, because one should only access these files via the Standard Interfaces to ensure consistency and backward compatibility of different versions.