There is only one file type that uses the .VTV extension:
Adobe Dreamweaver Validator Configuration File
Code validation file used by Adobe Dreamweaver, an application used to build Web applications; contains XML data that specifies valid uses of source code tags; used for reporting programming errors during development.
Dreamweaver includes several preinstalled VTV files for validating source code. For example, it includes an HTML validator file named html_all.vtv and a .JSP validator named jsp.vtv.
Updated: April 11, 2019