If in SSRS report I have numeric parameter @Parm1, and in the report I want it to appear as Parameter1: 12345, I achieve it by specifying textbox properties/number/Custom/Custom Format as "Parameter1:" 0.
But if the parameter is not numeric but a text, this does not work and "Parameter1:" is ignored. Is there some placeholder for the text values that would achieve that?
The reason I'm looking for formatting instead of specifying the value as an expression is because during the design it's much easier to see the actual parameter in each textbox instead of <Expr>.
You could do this with placeholders in the textbox, no need to apply formatting (although you could).
Delete what you have in the textbox then, click inside the textbox (twice I think) and then type the literal Parameter 1: after the space, right-click and select "insert placeholder" (or something similar, I'm doing this from memory) and then set the placeholder value expression to =Parameters!Parm1.Value.
In design mode it will look something like this
________________________
| Parameter 1: [Parm1] |
|______________________|
(forgive the dodgy sketch of a textbox!)