When a DASDL update requires the global data set to be reorganized because of a global item addition, deletion, or update, the programs accessing or updating data sets that have population items in the global data set must be recompiled. Otherwise, the programs get a version error when accessing or updating these data sets. This is true even though these data sets are not changed and the programs do not access the population items.

If the record contains a filler item, the filler item can be reduced in size or eliminated altogether, and new data items and group items can be added in the space made available.

The size of the record must not change. Thus, the filler item must be reduced in size or eliminated to produce the proper size area. Filler items are similar to alpha items. Their size is specified in 8‑bit bytes, they are aligned on byte boundaries, and they are initialized to all bits on. Regardless of the position of the filler item declaration, the filler in the record is located after all data items and group items, and before all control items.

Items added to a fixed-format record must be added at the end of the record. Items added to the fixed part of a variable-format record must be added at the end of the fixed part. Items added to the variable part must be added at the end of the variable part.

New items can be required and must not specify a null initial value. If new items are required, a reorganization also is required. If the new items are required and an initial value is not specified or the initial value is null, a data error occurs during the reorganization. All items added to existing records have the initial value of all bits on. This includes Boolean items and field items. All items in newly created records have normal initial values.

Since the filler item starts on an 8‑bit byte boundary, the first newly added item must start on a byte boundary also. If an unused 4‑bit digit precedes the filler, the first new item is not properly byte aligned. In this case, the error message “ITEM ADDED” or “ITEM MISMATCH” results. To avoid this problem, ensure that the first added item is byte aligned. For example, if one of the new items is an alpha item or group item, put it first. Otherwise, the first new item must be inserted in a dummy group item.

If an item is deleted from a data set or from global data, the item must also be deleted from all remaps which include it.