In 1994, a core group of ForthLanguage vendors and programmers drafted an ANSI standard for the ForthLanguage, based upon common practice at the time. It has also been adopted as an ISO and IEEE standard. Nowadays, any Forth implementation worth its salt complies with the standard, or at least provides an ANS compatibility layer. There is talk of creating a extension to the standard (http://www.forth200x.org) to incorporate common practice since its introduction.
By specifically describing word behavior rather than implementation, it freed vendors to explore many implementation options, leading to modern optimizing ForthCompilers that can still run code portably.
The ANSI standard is the basis for modern ForthPortability and ForthReusability. It was also the basis for OpenFirmware.