This program has been imported from the CPC Program Library held at Queen's University Belfast (1969-2018) Abstract In this paper we describe a HepML format and a corresponding C++ library developed for keeping complete description of parton level events in a unified and flexible form. HepML tags contain enough information to understand what kind of physics the simulated events describe and how the events have been prepared. A HepML block can be included into event files in the LHEF format. The structure of the HepML block is described by means of several XML Schemas. The Schemas define necessary informati... Title of program: libhepml Catalogue Id: AEGL_v1_0 Nature of problem Monte Carlo simulation in high energy physics is divided into several stages. Various programs exist for these stages. In this article we are interested in interfacing different Monte Carlo event generators via data files, in particular, Matrix Element (ME) generators and Showering and Hadronization (SH) generators. There is a widely accepted format for data files for such interfaces - Les Houches Event Format (LHEF). Although information kept in a LHEF file is enough for proper working of SH ge ... Versions of this program held in the CPC repository in Mendeley Data AEGL_v1_0; libhepml; 10.1016/j.cpc.2010.06.026