Changes and updates in recent versions of Lepto

introduced option to simulate scattering on intrinsic charm quarks, see LST(15).
additional options for applying cut-offs against divergences in QCD matrix elements, see LST(20).
new default values for QCD matrix element cutoffs PARL(8) and PARL(9).
new parameter PARL(10) for parton showers added on ME.
additional options of maximum virtuality for parton showers, see LST(9).
additional options, and new default, for treatment of the nucleon target remnant, see LST(14).
internal flag previously in LST(20) moved to LST(32), PARL(20) removed.
changed PY... to LY... in routine and common block names to avoid name clashes with Pythia.
corrected bug in treatment of azimuthal angle dependence in first order QCD matrix elements.

new treatment of sea quarks in the target remnant, see section 2.7 and LST(35).
implemented a model for soft colour interactions (SCI) as a mechanism to understand rapidity gap events, see section 2.8 and LST(34), PARL(7).
new default values for PARL(8),PARL(9),PARL(10) and PYPAR(22) in connection with having SCI as default.
Modified routines are LEPTOD, LINIT, LEPTO, LKINEM, LFRAME, LSHOWR, LMEPS, LYSSPA. New routines are LSCI, LECSWI, LEASWI.
Corrected bug in LFRAME, which only affected case of initial lepton with p_z<0 in collider mode.

changed the treatment (in LEPTO) when a matrix element event failes due to mass requirements; affects the cross section for heavy flavours.
additional options and new default for applying cut-offs against divergences in QCD matrix elements, see LST(20) and 2.5.
the new sea quark treatment is now used for all flavours up to LST(12).
new routine LSMALL introduced to handle small mass colour singlet systems including diquarks, see section 2.8.
new parameter, PARL(20), to decrease the masses of the remnant partons in case of a more complicated nucleon remnant than a simple diquark, see section 2.8.

additional option, and new default, for use of grid to store information that speed up the calculation of the probabilities for QCD-Compton- and BGF-events, see LST(19).
calculation speed of the probabilities for QCD-Compton- and BGF-events improved by a variable substitution in the integral.
corrected a bug in the subroutine LEPTO, which could affect the jet cross section.
a new parameter, PARL(12), regulates the probability for intrinsic charm, see section 2.4.

New option and default for the soft colour interactions, LST(34)=2. They now only occur between pairs of partons in the final state where one of the partons is from the proton remnant, i.e. no SCI between the perturbatively produced partons.
New option for the sea quark treatment LST(35)=2. The virtuality of the sea quark partner can now be selected from a gaussian of width PARL(10).