This datatype represents a variable-length string of characters.
The first character of a string is numbered one, not zero.
Theoretically, the string can contain null characters (i.e. character whose ASCII code is zero). But as some Gambas functions internally rely on zero-terminated strings, especially the methods of native class having string arguments, you should avoid them as much as possible!
Public sPub As String ' This string can be used by all subroutines in the same module
Public Sub Button1_Click()
Dim sLoc As String ' This string is local in this subroutine
sPub = "74zu88"
sLoc = Mid$(sPub, 3, 2)
If sLoc = "zu" Then Print "Expected"