The Web.SiteMap file is used to set up which high-level main menus are displayed to each role. These same menu items would then be used during the set up in the Web.config file. See Menu Security Setup Via the Web.SiteMap File for information on how to set this up. The following sample illustrates what this setup looks like, where the value for siteMapNode title is the high-level menu item.
<siteMapNode title="Account Management" roles="VP Admin,Buyer,Vendor Admin, Vendor,Program Control Analyst,Sub-Contractor Admin">