It seems like you're asking about a pattern in symbols that use two letters. There isn't a universal rule where the first letter always represents one thing and the second letter always represents another.

To figure out what you're looking for, I need a bit more information.

Could you please give me some examples of the symbols you're thinking about? Knowing what these symbols are used for would help me understand what you're trying to identify.

For example, are you thinking about:

* Chemical symbols: Like "He" for Helium or "Na" for Sodium.

* Units of measurement: Like "km" for kilometer or "kg" for kilogram.

* Abbreviations: Like "US" for United States or "UK" for United Kingdom.

* Codes: Like "QR" for Quick Response or "ID" for Identification.

Once I have a clearer idea of what you're asking, I can give you a more specific answer!