What Is a Fielded Buffer?

A fielded buffer is a data structure that provides associative access to the fields of a record.

Each field in an FML fielded buffer is labeled with an integer that combines information about the data type of the accompanying field with a unique identifying number. The label is called the field identifier, or fldid. For variable-length items, the fldid is followed by a length indicator.

A buffer can be represented as a sequence of fldid/data pairs, with fldid/length/data triples for variable-length items, as shown in the following diagram.

Fielded Buffer

In the header file that is included (with #include) whenever FML functions are used (fml.h or fml32.h), field identifiers are defined (with typedef) as FLDID (or FLDID32 for FML32), field value lengths as FLDLEN (FLDLEN32 for FML32), and field occurrence numbers as FLDOCC (FLDOCC32 for FML32).