%    FEYNMANDOC2E:  CHAPTER 2 PART E OF FEYNMANDOC.TEX  \include d there.
%
which renders:
\vskip 0.5in

\begin{picture}(15000,15000)(-2000,-12000)
\drawline\gluon[\E\FLIPPEDCURLY](0,0)[6]
\drawline\fermion[\NE\REG](\pbackx,\pbacky)[\gluonlengthx]
\drawline\fermion[\SE\REG](\pfrontx,\pfronty)[\gluonlengthx]
\drawline\fermion[\NE\REG](\pbackx,\pbacky)[\gluonlengthx]
\drawline\gluon[\W\FLIPPEDCURLY](\pfrontx,\pfronty)[6]
\drawline\fermion[\SW\REG](\pbackx,\pbacky)[\fermionlength]
\drawline\fermion[\NW\REG](\gluonbackx,\gluonbacky)[\fermionlength]
\drawline\fermion[\SW\REG](\pbackx,\pbacky)[\fermionlength]
\end{picture}

\hskip 3.5in

\begin{picture}(6000,15000)
\THICKLINES
\drawline\gluon[\S\REG](3000,14000)[8]
\drawline\fermion[\NE\REG](\pfrontx,\pfronty)[2000]
\drawline\fermion[\NW\REG](\pfrontx,\pfronty)[2000]
\drawline\fermion[\SE\REG](\gluonbackx,\gluonbacky)[2000]
\drawline\fermion[\SW\REG](\gluonbackx,\gluonbacky)[2000]
\end{picture}

\vskip 0.15in
As in the photonic case we use \bs gluonlengthx,y to draw fermion lines
which are the same length as gluon lines.  A word of caution.
Variables such as `\bs gluonlengthx' or `\bs photonlengthy' measure
the {\em displacements} of the line drawn and so may be either
positive or negative.  That is, \bs fermionlengthx will be positive
for fermions drawn in the E, NE or SE directions and negative for those
drawn in the W, NW and SW directions.  For N and S fermions it will vanish.
The length argument of \ddrawline, however, must be positive so caution is
advised.  The `\bs negate' command described in the section concerning
alignments in chapter four is often helpful.
The variables \bs {\it boxlengthx} and \bs {\it boxlengthy} may also be
used.  They are generally the absolute values of \bs particlelengthx
and \bs particlelengthy respectively (however see subsection 2.11.1).
These two values must never be altered by the user.
The variable `\bs fermionlength' is the total length of the
previously drawn fermion and so is always positive.
The second diagram merely demonstrates the \bs THICKLINES option when used
with gluons.  For further clarification of these points it may be useful to
review the previous section (PHOTONS).
