This warning occurs when the number specified for the UDF is not within the range specified.
Ensure the UDF is defined using the allowed range. Numbers falling between 1 to 9999 and 20001 to 65536 are opened for customisation, and those between 10000 to 20000 are allotted for Common development in TSPL.
UDF: String: 6553666
Here the number 6553666 is not within the allowed range. Hence the message warning T0022: The UDF number '6553666' used for 'UDF' is not in the allowed range appears.
The code is corrected by adding appropriate number.
UDF: String: 20004