Topic: ASP.NET 1.0: VS2015 and SSI - how to work?

Children,  as though simple and practical on the tool: I write a site ASP.NET 1.0 (i.e. to a treasure *.aspx  directly on the server, it  and executes them). In some pages there is a repeating code which gets variables, does checks, etc. As most simple, I interposed it through SSI (and such insertions will be a little and everywhere different). But here an ambush: If the directive <% Page Language = "C#" Debug = "true" %> to hold in a principal file the connected file cannot contain it any more. But if to open a connected file in studio, she in an emphasis does not understand it (even with aspx extension) - does not highlight! I.e. the question costs so: how to have illumination and  in a connected file? PS if the directive of instructions of language to carry out in the very first SSI already principal page "does not see" ASP (i.e. I  does not highlight the code). PPS To what generally such  with "the language directive can be only one"? If directives two, but language - the same, in what a problem? PPPS time MS guessed to restrict the language directive can then it was necessary to give adjustment in studio "all ASP pages to imply with C# the code"? (Whether as for **** they with the BASIC! There would be no it a nausea - and the directive would be not necessary!) Perhaps any other editor is able to edit correctly SSI ?