Rules for Control Level Indicators

When you assign control level indicators, remember the following:

• You can specify control fields only for primary or secondary files.
• You cannot specify control fields for full procedural files; numeric input fields of type binary, integer, unsigned or float; or look-ahead fields.
• You cannot use control level indicators when an array name is specified in positions 49 through 62 of the input specifications; however, you can use control level indicators with an array element. Control level indicators are not allowed for null-capable fields.
• Control level compare operations are processed for records in the order in which they are found, regardless of the file from which they come.
• If you use the same control level indicator in different record types or in different files, the control fields associated with that control level indicator must be the same length (see Figure 15) except for date, time, and timestamp fields which need only match in type (that is, they can be different formats).
• The control level indicator field length is the length of a control level indicator in a record. For example, if L1 has a field length of 10 bytes in a record, the control level indicator field length for L1 is 10 positions.

  The control level indicator field length for split control fields is the sum of the lengths of all fields associated with a control level indicator in a record. If L2 has a split control field consisting of 3 fields of length: 12 bytes, 2 bytes and 4 bytes; then the control level indicator field length for L2 is 18 positions.

  If multiple records use the same control level indicator, then the control level indicator field length is the length of only one record, not the sum of all the lengths of the records.

  Within a program, the sum of the control level indicator field lengths of all control level indicators cannot exceed 256 positions.

• Record positions in control fields assigned different control level indicators can overlap in the same record type (see Figure 16). For record types that require control or match fields, the total length of the control or match field must be less than or equal to 256. For example, in Figure 16, 15 positions have been assigned to control levels.
• Field names are ignored in control level operations. Therefore, fields from different record types that have been assigned the same control level indicator can have the same name.
• Control levels need not be written in any sequence. An L2 entry can appear before L1. All lower level indicators need not be assigned.
• If different record types in a file do not have the same number of control fields, unwanted control breaks can occur.

Figure 17 shows an example of how to avoid unwanted control breaks.

*...1....+....2....+....3....+....4....+....5....+....6....+....7...
A* EMPLOYEE MASTER FILE -- EMPMSTL
A          R EMPREC                    PFILE(EMPMSTL)
A            EMPLNO         6
A            DEPT           3
A            DIVSON         1
A*
A*                 (ADDITIONAL FIELDS)
A*
A          R EMPTIM                    PFILE(EMPMSTP)
A            EMPLNO         6
A            DEPT           3
A            DIVSON         1
A*
A*                 (ADDITIONAL FIELDS)
*...1....+....2....+....3....+....4....+....5....+....6....+....7...
IFilename++SqNORiPos1+NCCPos2+NCCPos3+NCC................................
I........................Fmt+SPFrom+To+++DcField+++++++++L1M1FrPlMnZr....
 *
 *  In this example, control level indicators are defined for three
 *  fields.  The names of the control fields (DIVSON, DEPT, EMPLNO)
 *  give an indication of their relative importance.
 *  The division (DIVSON) is the most important group.
 *  It is given the highest control level indicator used (L3).
 *  The department (DEPT) ranks below the division;
 *  L2 is assigned to it.  The employee field (EMPLNO) has
 *  the lowest control level indicator (L1) assigned to it.
 *
IEMPREC        10
I                                          EMPLNO        L1
I                                          DIVSON        L3
I                                          DEPT          L2
 *
 *  The same control level indicators can be used for different record
 *  types.  However, the control fields having the same indicators must
 *  be the same length.  For records in an externally described file,
 *  the field attributes are defined in the external description.
 *
IEMPTIM        20
I                                          EMPLNO        L1
I                                          DEPT          L2
I                                          DIVSON        L3

Figure 16. Overlapping Control Fields

Figure 17. How to Avoid Unwanted Control Breaks

*...1....+....2....+....3....+....4....+....5....+....6....+....7...
IFilename++SqNORiPos1+NCCPos2+NCCPos3+NCC................................
I........................Fmt+SPFrom+To+++DcField+++++++++L1M1FrPlMnZr....
ISALES         01
I                                  1    2  L2FLD         L2
I                                  3   15  NAME
IITEM          02
I                                  1    2  L2FLD         L2
I                                  3    5  L1FLD         L1
I                                  6    8  AMT
CL0N01Factor1+++++++Opcode(E)+Factor2+++++++Result++++++++Len++D+HiLoEq..
 *  Indicator 11 is set on when the salesman record is read.
 *
C   01              SETON                                        11
 *
 *  Indicator 11 is set off when the item record is read.
 *  This allows the normal L1 control break to occur.
 *
C   02              SETOFF                                       11
C   02AMT           ADD       L1TOT         L1TOT             5 0
CL1   L1TOT         ADD       L2TOT         L2TOT             5 0
CL2   L2TOT         ADD       LRTOT         LRTOT             5 0
 *

*...1....+....2....+....3....+....4....+....5....+....6....+....7...
OFilename++DF..N01N02N03Excnam++++B++A++Sb+Sa+...........................
O..............N01N02N03Field+++++++++YB.End++PConstant/editword/DTformat
OPRINTER   D    01                  1  1
O                       L2FLD                5
O                       NAME                25
O          D    02                     1
O                       L1FLD               15
O                       AMT           Z     15
 *
 *  When the next item record causes an L1 control break, no total
 *  output is printed if indicator 11 is on.  Detail calculations
 *  are then processed for the item record.
 *
OFilename++DF..N01N02N03Excnam++++B++A++Sb+Sa+...........................
O..............N01N02N03Field+++++++++YB.End++PConstant/editword/DTformat
O          T    L1N11               1
O                     L1TOT           ZB    25
O                                           27 '*'
O          T    L2                  1
O                     L2TOT           ZB    25
O                                           28 '**'
O          T    LR                  1
O                     LRTOT           ZB    25

Different record types normally contain the same number of control fields. However, some applications require a different number of control fields in some records.

The salesman records contain only the L2 control field. The item records contain both L1 and L2 control fields. With normal RPG IV coding, an unwanted control break is created by the first item record following the salesman record. This is recognized by an L1 control break immediately following the salesman record and results in an asterisk being printed on the line below the salesman record.

• Numeric control fields are compared in zoned decimal format. Packed numeric input fields lengths can be determined by the formula:

  d = 2n - 1

  Where d = number of digits in the field and n = length of the input field. The number of digits in a packed numeric field is always odd; therefore, when a packed numeric field is compared with a zoned decimal numeric field, the zoned field must have an odd length.
• When numeric control fields with decimal positions are compared to determine whether a control break has occurred, they are always treated as if they had no decimal positions. For instance, 3.46 is considered equal to 346.
• If you specify a field as numeric, only the positive numeric value determines whether a control break has occurred; that is, a field is always considered to be positive. For example, -5 is considered equal to +5.
• Date and time fields are converted to *ISO format before being compared
• Graphic data is compared by hexadecimal value