There are two ways to specify field length. If a field has a constant length that is defined in the control file with a position specification or the data type and length, then it has a predetermined size. If a field's length is not known in advance, but depends on indicators in the record, then the field is delimited, using either enclosure or termination delimiters.
If a position specification with start and end values is defined for a field that also has enclosure or termination delimiters defined, then only the position specification has any effect. The enclosure and termination delimiters are ignored.
Fields that have a predetermined size are specified with a starting position and ending position, or with a length, as in the following examples:
loc POSITION(19:31) loc CHAR(14)
In the second case, even though the exact position of the field is not specified, the length of the field is predetermined.
Delimiters are characters that demarcate field boundaries.
Enclosure delimiters surround a field, like the quotation marks in the following example, where "__" represents blanks or tabs:
"__aa__"
Termination delimiters signal the end of a field, like the comma in the following example:
__aa__,
Delimiters are specified with the control clauses TERMINATED BY and ENCLOSED BY, as shown in the following example:
loc TERMINATED BY "." OPTIONALLY ENCLOSED BY '|'