Why is Microsoft involved in HD DVD?
Microsoft supports HD DVD because the mandatory player features such as persistent storage, picture-in-picture, and network connectivity lead to greater interactivity and a better, more consistent user experience.  Read more in the white paper available at ThisIsHDDVD.com: https://www.thisishddvd.com/Downloads/WhatIsHDDVD.pdf

What is HDi?
HDi is Microsoft's implementation of advanced interactivity for HD DVD.  Players that license HDi (such as Toshiba players and Xbox) may carry the HDi logo.  HDi is a trademarked name.  Players that use an implementation of advanced interactivity that is not Microsoft are not running HDi. 


Where do I download the HDi simulator?
The HDi simulator is included in the Interactivity Jumpstart kit available at: https://www.microsoft.com/downloads/details.aspx?FamilyId=F8ADA3F5-0EC6-4392-84AB-CB4860DB30ED&displaylang=en

How do I install the Interactivity Jumpstart Kit on Vista?
For more information, read: https://blogs.msdn.com/amyd/archive/2007/04/14/installing-hd-dvd-interactivity-jumpstart-on-vista.aspx

What tools are available for authoring a complete HD DVD with advanced content?
Creation on an HD DVD with advanced content requires a tool for encoding like Sonic's CineVision or Telestream's Episode Pro and a multiplexing tool like Sonic's Advanced Content Creation or Corel's Multiplexer available from NetBlender.  Read more about authoring HD DVDs with advanced content in the white paper available at ThisIsHDDVD.com: https://www.thisishddvd.com/Downloads/MakingHDDVDs3.pdf.

What tools are available for authoring a complete HD DVD with standard content?
For more information, read: https://blogs.msdn.com/ptorr/archive/2007/05/12/hd-dvd-creation-on-the-mac-and-pc.aspx

Development and Resources

Where can I get a copy of the DVD Specifications for High Definition VIDEO?
The specification was created by the DVD Forum and is available from the DVD Formart/Logo Licensing Corporation.  For more information, visit: https://www.dvdfllc.co.jp/format/f_nosbsc.html.

Where can I find a list of all the ECMASCript objects and methods used in advanced interactivity for HD DVD? Annex Z of the DVD Specifications for High Definition VIDEO goes into depth on the objects, methods, members, exceptions, and external specification references used in advanced content. 

An object model diagram is also available in Visio and .png format in the Documentation directory when you install the Interactivity Jumpstart Kit.

What is an ACA?
ACAs are archive files.  By grouping your application files into a single ACA file, you reduce the number of seeks required by the laser and more efficiently utilize the player's filecache.  For more information on ACA files, read https://blogs.msdn.com/amyd/archive/2007/05/09/acas-are-your-friend.aspx or https://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=1823600&SiteID=1

What functionality is restricted on a non-AACS HD DVD?
Networking and use of persistent storage is currently restricted to AACS discs.  In the future, application signing may allow these features on non-AACS discs.  Further details on these restrictions can be found in Annex X of the DVD Specifications for High Definition VIDEO.

Where can I find the meaning of an error code displayed on a Toshiba or Xbox HD DVD Player?