It's what used to be used to show the variable type. below is from VB3 help.
The following table shows the fundamental data types supported by Visual Basic, and the type-declaration suffix, storage size, and range of each data type. This form has shuffled it a bit, hope it makes sense.
Data type Suffix Storage size Range
Integer % 2 bytes -32,768 to 32,767.
Long
(long integer) & 4 bytes -2,147,483,648 to 2,147,483,647.
Single
(single-precision floating-point) ! 4 bytes -3.402823E38 to -1.401298E-45 for negative values; 1.401298E-45 to 3.402823E38 for positive values.
Double
(double-precision floating-point) # 8 bytes -1.79769313486232E308 to
-4.94065645841247E-324 for negative values; 4.94065645841247E-324 to 1.79769313486232E308 for positive values.
Currency
(scaled integer) @ 8 bytes -922,337,203,685,477.5808 to 922,337,203,685,477.5807.
String $ 1 byte per character 0 to approximately 65,500 bytes. (Some storage overhead is required.)
Variant None As appropriate Any numeric value up to the range of a Double or any character text.
User-defined (using Type) None Number required by elements The range of each element is the same as the range of its fundamental data type, listed above.