ALTO (Analyzed Layout and Text Object) is a XML Schema that details technical metadata for describing the layout and content of physical text resources, such as pages of a book or a newspaper. It most commonly serves as an extension schema used within the Metadata Encoding and Transmission Schema (METS) administrative metadata section. However, ALTO instances can also exist as a standalone document used independently of METS.
textMD is a XML Schema maintained by the Library of Congress that details technical metadata for text-based digital objects. It allows for detailing properties such as encoding information (quality, platform, software, agent), character information (character set and size, byte order and size, line terminators), languages, fonts, markup information, processing and textual notes, technical requirements for printing and viewing, and page ordering and sequencing.