Syntax: PTYPE n s
or      PTYPE pexpr
or      PTYPE WORD
or      PTYPE { list }

   PTYPE n s causes points to be drawn as n sided polygons of a style s,
where s refers to:
        0 = open 
        1 = skeletal (center connected to vertices)
        2 = starred
        3 = solid
For example, PTYPE 1 1 makes points appear as dots, PTYPE 4 1 makes
(diagonal) crosses, and PTYPE 6 3 makes filled hexagons. Points made
up of lines (types 0, 1, and 2) are drawn using the current LTYPE.

   PTYPE pexpr uses vector WORD as its source of n and s, except that
the numbers are contracted together. (`Pexpr' is the name of a vector,
or an expression in parentheses, e.g. PTYPE (y+10) or PTYPE y). If the
entry has a fractional part, it is treated as an expansion factor (no
fractional part means default expansion).  For example, an an entry of
103.5 in WORD is the same as PTYPE 10 3, EXPAND 0.5. This expansion is
relative to the current EXPAND. It's much easier to use a vector of
expansions directly to the EXPAND command, but fractional ptypes are
preserved for backwards compatibility.

   If WORD in PTYPE WORD is an arithmetic vector it's interpreted as in
the previous paragraph. On the other hand, if it's a vector of strings
they are taken to be the labels to use for points. When you issue a
POINTS command they are written at the current expansion and angle at
the points (essentially using a PUTLABEL 5 command). As usual, the
font used is specified by the variable default_font which you can set
in your .sm file (it's only available for TeX_strings users
though).

   PTYPE with a list in braces defines a symbol to be drawn with the
POINTS command. The list is taken to be a set of coordinates relative
to the current point. If an (x,y) pair is preceeded by `m' (move) or
`r' (relocate), no line is drawn but the current pointer is moved to
(x,y). If the pair is preceeded by a `d' (draw) or nothing, then a
line is drawn from the previous point to (x,y). The coordinates are
given in screen units (i.e. the complete device is 0-32767 on a side).
For example, `PTYPE { r 200 0 0 200 -200 0 0 -200 200 0 }' will define
diamond, similar to `PTYPE 4 0 angle 45'. ANGLE and EXPAND apply as
usual.