Synopsis
In calling some function, you specified an arg that is not just a single character, for example "Hello" instead of "H". name is the function you called which is complaining about the arg. number tells which arg was not a single character (where 1 is the first arg). bad arg is what you supplied.
Cause
You wanted to specify your arg as a literal string, but you forgot to put quotes around it. Therefore, Reginald assumes that it is the name of a variable which contains the real value. And that variable was previously assigned a value that is not just a single character. This is likely the case if bad arg is not what you intended.
Cure
If you're directly supplying your arg as a literal string, put quotes around it.
Cause
You stored the value in a variable, and then when passing that, you put the name of that variable in quotes, thus mistakenly passing the variable's name rather than its value. This is likely the case if bad arg is your variable name.
Cure
Do not put your variable name in quotes.
Cause
You specified a variable name, but that variable was never assigned any value. Therefore, its default value is its name in capital letters. This is likely the case if bad arg is the name of your variable in capital letters.
Cure
Make sure that you assign a value to the variable before calling the function. You can trap the NOVALUE condition to catch errors of this nature.