Final answer:
Mnemonic codes are appropriate for items in either an ascending or descending sequence.
Step-by-step explanation:
Mnemonic codes can be used to remember items in an ascending or descending sequence, such as the numbering of checks or source documents. This statement is true. Mnemonic devices are memory aids that help us organize and recall information. In this case, mnemonic codes can be used to create a memorable pattern or keyword that represents the sequence of numbers, making it easier to remember and retrieve the correct order.