syscolumns.collength for DATATIME?

Page 2-18 of the Informix Guide to SQL: Reference Manual defines the formula for column syscolumns.collength for DATETIME values as follows: (length * 256) + (largest_qualifier_value * 16) + max_size Does anyone have pseduo-code that will calculate what *length* is if I know the value of syscolumns.collength? Would somthing like this work?: smalled_qualifier_value = syscolumns.collength % 16 temp = syscolumns.collength - smalled_qualifier_value largest_qualifier_value = temp % 256 temp = temp - largest_qualifier_value length = temp / 256 I'm trying to write a ESQL/C program that will give me the total key length for each index on a table. "dbschema" will give a sum of all indexes for a table in the comment for the table, but does not give the individual index key lengths. Is there a better way to get that information besides querying the system catalog tables directly? TIA.