A webserver environment as with Apache or Nginx includes a type of file (or a file system) that I can call a webserver substrate; In Apache it is called a Virtual host and in Nginx I can call it a "Block system", mainly comprised of a server{}
block, among other blocks.
This "webserver substratre" connects an app's directory with the webserver, and also enables or disables it (by means of webserver requests and responses associated with that app directory). Thus, each web application has one such substrate.
What is the common term for such file, or file system, in the Linux System Administration (LSA) field?