All PERCON functions involve data transfer. A distinction is made between three basic functions and five subsidiary functions.
The three basic functions comprise:
copying files
editing tapes
duplicating tapes.
These functions are distinguished by the access method for the input and output data.
Basic function | Access to | |
Input data | Output data | |
Copying files | Logical | Logical |
Editing tapes | Physical | Logical |
Duplicating tapes | Physical | Physical |
In the case of logical access, files are accessed via their file name. The units to be processed are records; they are processed in their logical order.
In the case of physical access, tapes and tape cartridges are accessed via their volume serial number (VSN). The units to be processed are blocks; they are processed in their physical order.
The basic functions may be complemented by five subsidiary functions; these five functions comprise:
selecting records
formatting records
editing records and blocks
forming groups of records
positioning tapes.
The following combinations of basic functions and subsidiary functions are allowed:
Subsidiary function | Basic functions | ||
Copying files | Editing tapes | Duplicating tapes | |
Selecting | + | + | - |
Formatting | + | - | - |
Editing | + | + | - |
Grouping | + | - | - |
Positioning | - | + | - |
+ permissible combination
- illegal combination