If present, the long variable names record has the following format:
/* Header. */
int32 rec_type;
int32 subtype;
int32 size;
int32 count;
/* Exactly count bytes of data. */
char var_name_pairs[];
int32 rec_type;Record type. Always set to 7.
int32 subtype;Record subtype. Always set to 13.
int32 size;The size of each element in the var_name_pairs member. Always set to 1.
int32 count;The total number of bytes in var_name_pairs.
char var_name_pairs[];A list of key–value tuples, where key is the name
of a variable, and value is its long variable name.
The key field is at most 8 bytes long and must match the
name of a variable which appears in the variable record (see Variable Record).
The value field is at most 64 bytes long.
The key and value fields are separated by a ‘=’ byte.
Each tuple is separated by a byte whose value is 09. There is no
trailing separator following the last tuple.
The total length is count bytes.