XyQuest Signature is a DOS word processor made by XyQuest as a successor for the successful XyWrite III+ word processor. This version was originally dubbed "IBM Signature" as it was commanded by IBM to be a part of the company's foray into application software. IBM scrapped the project and XyQuest tried to market Signature under its own name. Signature is a transitional program that has many technological innovations (compared to XyWrite III+) and showed the way to XyWrite IV, which was more appreciated by loyal followers and is still used by some DOS aficionados. XyQuest went under in 2001, but the same code base still lives in NotaBene (an academic word processor) and ATEX (originally a DEC minicomputer newspaper production system from which XyWrite is ultimately derived) still used by media houses around the world.

The program can be installed under modern Windows (even 64-bit) operating systems by using vDosPlus-based DOS virtualization solutions. There is even a dedicated installer for this purpose: http://users.datarealm.com/xywwweb/