How to define Latex fonts \mathsf in macros?

Simple question. I’d like to define macros vp which is \mathsf{p} in Latex terms. I can not find info about this in the manual. Could somebody explain? I try to use Tools -> New Macro. But in the window, there is no info.

To learn TeXmacs equivalents of LaTeX constructs you can try to import simple documents or “Paste to LaTeX” inside TeXmacs. In this case just copy “\mathsf{p}” and then “Paste to LaTeX” to see that inside TeXmacs the equivalent tag is \math-ss. HTH.

Thank you, good idea. I found this equivalent by importing Latex file with this macros and looking texmacs source. Could you explain me how to use Tools-> Macros -> New Macro to make macro mathsf{p}. What I have to print in the window? I tried \math-ss but after return everything disappears.

On my setup some keys you need to edit macros without toolbars (as needed in the macro editor) do not work, so I do not use it. You can go to the preamble of the document via Document->Part->Create Preamble and there create the macro via something like
<assign|mathsf|<macro|x|<math-ss|<arg|x>>>>
You may want to give a look at the help to have an introduction to the stylesheet language.