The electronic version of this International Standard can be downloaded from the ISO/IEC Information Technology Task Force (ITTF) web site.
ISO/IEC 29500-3:2015 defines a set of conventions for forward compatibility of markup specifications, applicable not only to Office Open XML specifications as described in Parts 1 and 4 of this Standard, but also to other markup specifications. These conventions allow XML documents created by applications of later versions or extensions to be handled by applications of earlier versions.