Exec keyLegacy-Mixed Encoding (Deprecated)Exec keyLegacy-Mixed Encoding (Deprecated)
      If the standard is to be amended with a new {key,value} pair which
      should be applicable to all supporting parties, a group discussion
      will take place.  This is the preferred method for introducing
      changes.  If one particular party wishes to add a field for personal
      use, they should prefix the key with the string X-PRODUCT,
      e.g. X-NewDesktop-Foo, following the precedent set by other IETF and RFC
      standards.
    
      Alternatively, fields can be placed in their own group, where they may
      then have arbitrary key names.  If this is the case, the group should
      follow the scheme outlined above,
      i.e. [X-PRODUCT
      GROUPNAME] or
      something similar.  These steps will avoid namespace clashes between
      different yet similar environments.