Radio Shack TRS-80 PC-3 Owner's Manual page 172

For example, "####" is an editing specification for a right-justified numeric field with room for 3 digits and the sign. In numeric
fields, a location must be included for the sign, even if it will always be positive.
Editing specifications may include more than one field. For example, "####&&&&" could be used to print a numeric and a
character field next to each other.
If the editing specifications is missing, as in format 1, special formatting is turned off and the built-in display rules pertain.
Examples
Display
10 A
=
125 : X$
=
"ABCDEF"
20 PRINT USING "##.##"''''''; A
30 PRINT USING "&&&&&&&&"; X$
40 PRINT USING "####&&&";A;X$
172
ABCDEF
125ABC
1.25E 02