Final answer:
When a firm wants its coding system to convey meaning without reference to any other document, it would choose a mnemonic coding system.
Step-by-step explanation:
Mnemonic codes are those codes that consist of alphabets or abbreviations as symbols for codifying a piece of information.
This system uses a combination of letters and numbers to represent concepts, allowing the code itself to provide information about the item it represents without needing to consult additional documentation.
For example, Book codes in a library can be designed to reflect genres, authors, or publication years at a glance. In a coding system where signs or symbols are intuitive or self-explanatory, each symbol functions on its own to deliver a specific meaning, resonant of how pictographic writing systems or ideograms operate, conveying complex ideas through simple representations.