@Section
   @Title { Margins }
@Begin
@PP
@Code "@Tab" places a @I { vertical margin } above and below each row, and a
margins.tables @SubIndex { in tables }
@I { horizontal margin } to the left and right of each column.  (If there are
no side rules, the leftmost and rightmost margins are omitted.)  The size of
these margins is determined by two options to the @Code "@Tab" symbol:
@ID @OneRow @Code {
"@Tab"
"    hmargin { 0.3c }"
"    vmargin { 0.2v }"
"    @Fmta { ... }"
"..."
}
Shown here are the default values, 0.3 centimetres for the horizontal
margins, and 0.2 times the current inter-line spacing (denoted by the
letter {@Code v}) for the vertical margins.
@PP
The horizontal margin is fixed, but each row may have its own vertical margin:
@ID @OneRow @Code {
"@Rowa"
"    vmargin { 0.5vx }"
"    A { ... }"
}
If omitted, the @Code vmargin value is taken from the @Code "@Tab" option.
@PP
The value shown here, {@Code "0.5vx"}, requests a vertical margin of
half the current inter-line spacing, measured from the baseline of the
entry rather than from its edge (this is what the @Code x means).  This
value is a good choice when the entries contain simple words or lines
of text (i.e. no paragraphs, large equations, figures, etc.):
@CD {
@Tab
    vmargin { 0.5vx }
    @Fmta { @Col @Heading A  !  @Col @Heading B }
    @Fmtb { @Col A  !  @Col @CC B }
{
    @Rowa A { Course } B { Enrolment }
    @Rowb A { Software Engineering } B { 174 }
    @Rowb A { Complexity Theory } B { 37 }
}
}
since the lines of the table will then be separated evenly like
the lines in paragraphs.
@End @Section
