The sort-merge file description entry (SD entry) represents
the highest level of organization in the file section.
The sort-merge file description entry furnishes information concerning
the physical structure pertaining to a sort or merge file.
The clauses of a sort-merge file description entry (SD entry)
specify the size and the names of the records associated with a sort file or
a merge file.
SD file-name-1
[ RECORD [ CONTAINS ] [ integer-1 TO ] integer-2 [ CHARACTERS ]