Release 10.1A: OpenEdge Development:
Progress 4GL Reference

CRC-VALUE attribute

The cyclic redundancy check (CRC) value for either an r-code file, or a database table corresponding to a buffer object.

Data type: INTEGER

Access: Readable

Applies to: Buffer object handle, RCODE-INFO system handle

When applied to the RCODE-INFO system handle, the r-code CRC is calculated using the filename and contents of the r-code file specified by the RCODE-INFO:FILE-NAME attribute.

When applied to the Buffer object handle, the database CRC is calculated using the metaschema _CRC field value from the _File record for the database record corresponding to the buffer object's table (which can be a standard or temporary table).

The CRC for a temporary table is calculated differently than for a standard table. Some differences include:

Standard tables have a _File record in the database that contains a _CRC field for the CRC value, which is calculated as you make changes to the table. Temporary tables do not have a _File record, and do not exist in a database.
The CRC values for both standard and temporary tables include the datatype, extent and position of each column in the table, as well as index information. However, the CRC value for a standard table includes additional information that a CRC value for a temporary table does not (such as, the _Order field in the _File record).
The CRC value for a standard table is stored in a .r file. Progress uses that CRC value at runtime to verify the integrity of application r-code that uses the table. Progress uses the CRC value for a temporary table to compare table parameters between a calling and called procedure (to avoid a field-by-field comparison).

For more information on CRCs, see OpenEdge Deployment: Managing 4GL Applications .