Alpha Data Validation

With alpha data, bad characters are usually replaced with a question mark (?) instead of the whole field being set to NULL. The client configuration file parameter inhibit_ctrl_chars determines whether or not control characters are to be treated as bad characters (the program treats a few control characters such as NUL, CR and LF as bad regardless of the value of this parameter). The client configuration file parameter inhibit_8_bit_data determines whether or not 8-bit characters are to be treated as bad characters. The client configuration parameter convert_ctrl_char (which is incompatible with inhibit_ctrl_chars) replaces control characters by spaces instead or question marks. For more information, see convert_ctrl_char.

The client configuration file parameter alpha_error_cutoff determines the percentage of bad characters in an ALPHA field that are tolerated before the entire field is declared bad and treated as NULL.

If ALPHA data is stored as binary data, no alpha data validation is performed because no invalid values exist in binary data. See the DIOPT_Clone_as_Binary option in the di_options column of DMS_ITEMS.

NULL data is stored as NULL if the da_options column of the corresponding DATAITEMS control table entry has the DAOPT_Allow_Nulls bit (1) set. Otherwise, the NULL data is stored as blanks.