This invention relates to a system, method and computer program product for parsing a message against a message model, the message model including a choice block of element options and guide field for guiding the parse, the method including: parsing a message against a message model until the choice block of element options and associated guide field is located in the message model; determining element options associated with a particular guide field value located in the message, each element option having an associated frequency of occurring within a body of messages; choosing the most frequently occurring element option for the located guide field value; and further parsing the choice block of element options against the chosen element option.