ISO 6709 Standard representation of geographic point location by coordinates is the international standard for representation of latitude, longitude and altitude for geographic point locations.
The first edition (ISO 6709:1983) was developed by ISO/IEC JTC 1/SC 32. Later the standard was transferred to ISO/TC211, Geographic information/Geomatics in 2001. The committee completely revised the second edition (ISO 6709:2008).
The second edition consists of a main part and eight annexes (Annexes A through H). The main part and Annexes A and C give encoding-independent general rules to define items to specify geographic point(s). Annex D suggests a display style for human interface. Annexes F and G suggest styles of XML expression. Annex H suggests string expression, which supersedes the first edition of the standard.
Read more about ISO 6709: Representation At The Human Interface (Annex D), XML Representation (Annex F), String Expression (Annex H)