`@<>`

s: it specifies how far "sideways" the arrow should be
moved, will typeset\xymatrix{ A \ar@<1ex>[dr]^a_{.} \\ & B \ar@<1ex>[ul]^b \ar@<1ex>[r]^c & C \ar@<1ex>[l]^d_{.} }

A positive distance will slide the arrow in the "`^`

-direction," *e.g.*,
the two arrows above are slid in the direction of the labels *a*,
*b*, *c*, and *d*, respectively; a negative distance in the
"`_`

-direction." The distance `<@1ex>`

is often appropriate since it
corresponds roughly to the height of letters like "x," in the type size
being used.

© Kristoffer H. Rose <krisrose@brics.dk> December 19, 1996 / LaTeX2