Final answer:
The valid user-defined format names are likely '$STFMT', '_4YEARS', and 'SALRANGES', as they adhere to general naming conventions of starting with a letter or underscore and not starting with a number.
Step-by-step explanation:
When determining valid user-defined format names, there are certain rules and conventions that must be followed, which often depend on the programming language or software in question. Generally, valid format names cannot start with a number and must not contain spaces. They may include alphabetic characters, some special characters, and possibly numbers after the first character.
In the list provided:
- '$STFMT' is valid because it starts with a character and contains all capital letters and a special character that is generally accepted.
- '$3LEVELS' is not valid because it starts with a number, which is typically not allowed.
- '_4YEARS' is valid as it starts with an underscore, which is usually a permitted special character, followed by alphanumeric characters.
- 'SALRANGES' is valid since it only contains alphabetic characters.
- 'DOLLAR' is likely invalid as a format name because it is a common keyword in many systems that is used to represent currency and may be reserved. However, its validity could depend on the specific context and whether the system allows for such common words to be used as format names.
Therefore, '$STFMT', '_4YEARS', and 'SALRANGES' are most likely the valid user-defined format names among the options given.