No specific info about version 3.1. Please visit the main page of XML Authoring Guide on Software Informer.
It helps you convert XML to other database and document formats.
It is a designed for authoring, exploring, checking or validating XML docs.
XMLFox Visual Studio XML Editor is the best XML editor for years.
It allows you to create Hollywood-style Blu-ray Disc 3D products.
Macrobject Help Authoring Suite (MOHAS) is a suite of help authoring tools.
Liquid XML Studio allows you to create and edit XML documents.