The description of smf format expansion
The smf file is a math formula created by OpenOffice and other variants of the office suite. The smf file stores the syntax and formatting of a mathematical equation or expression. Starting from StarOffice 6.0 version replaced with the newer odf format, but is still supported by Apache OpenOffice.
The SMF format was originally used by StarMath through StarMath version 5. StarMath 6 and Apache OpenOffice version 1 adopted the sxm format , which was later replaced by the OpenDocument ODF format. Apache OpenOffice still supports the SMF format even though it has been deprecated.