NAME
     AddRibbon - add ribbons (schematic drawing)

SYNOPSIS
     AddRibbon

DESCRIPTION
     Create a schematic drawing with ribbons. The ribbons
     will go through the currently selected atoms, this
     will normally be all CA atoms in a protein.

     If ribbons for helices and sheets are desired, certain
     properties of the residues must be set to give the
     necessary secondary structure information. The
     following properties are used:

	 helix
	 helix1, helix2,...
	 sheet
	 sheet1, sheet2,...
	 strand1_1, strand1_2,...

     These properties are set when a PDB file containing
     secondary structure information (HELIX and SHEET
     records) is read, or they can be calculated with the
     CalcSecondary command. They can also be set/modified
     using the DefPropRes command, a more convenient way
     for modifying the result of CalcSecondary is often to
     use the WriteSecondary command.

     For sheets, the neighbour of the residues should be
     set with the SetNeigh command if the secondary
     structure was not read from a PDB file or calculated
     with CalcSecondary.

     The created primitives will have exactly one of the
     following properties set:

	 helix
	 sheet
	 coil

     and for helix and sheet the numbered one from the 
     residue (helix1,...) is also copied.

     In addition, all created primitives have the property
     "ribbon".

EXAMPLE
     AddRibbon

SEE ALSO
     ReadPdb, CalcSecondary, SelectAtom,
     WriteSecondary, DefPropRes, SetNeigh,
     LengthPrim, ColorPrim, TintPrim, ShadePrim,
     TypeRibbon, StyleRibbon, SizeRibbon, PaintRibbon
     LengthBond, RemovePrim

DATE
     970723
