Processing Control ($C, $L, $R, $E)

The $C, $L, $R, and $E metacharacters influence the mapping process, controlling whether and when the mapping process terminates. The metacharacter:

• $C causes the mapping process to continue with the next entry, using the output string of the current entry as the new input string for the mapping process.

• $L causes the mapping process to continue with the next entry, using the output string of the current entry as the new input string for the mapping process, and, if no matching entry is found, making one more pass through the table starting with the first table entry; a subsequent matching entry with a $C, $E, or $R metacharacter overrides this condition.

• $R causes the mapping process to continue from the first entry of the table, using the output string of the current entry as the new input string for the mapping process.

• $E causes the mapping process to terminate; the output string of this entry is the final output. $E is the default.

Mapping table templates are scanned left to right. To set a $C, $L, or $R flag for entries that may “succeed” or “fail” (for example, general database substitutions or random-value controlled entries), put the $C, $L, or $R metacharacter to the left of the part of the entry that may succeed or fail; otherwise, if the remainder of the entry fails, the flag is not seen.