[Groff] breaking long .FG figure captions?

[Anton Shterenlikht]

In this fragment of a troff document
build on FreeBSD 10.0-current
with
        pic z.1 |eqn|groff -mm > z.ps 

I have a multi-line caption:

.DS CB
.PIC -C rep-peeq-srf.ps 5.0
.FG "Equivalent plastic strain ahead of the notch (if any) for all models at 
$-196 sup{0}$C at the surface at $epsilon sub{p} = 0.2%$ or shortly after." "" 
0 fig:peeq-srf
.SETR fig:peeq-srf
.DE

which I'd like to break into several shorter
lines, but this doesn't seem to work:

.DS CB
.PIC -C rep-peeq-srf.ps 5.0
.FG "Equivalent plastic strain ahead\
 of the notch (if any) for all models at\
 $-196 sup{0}$C at the surface at\
 $epsilon sub{p} = 0.2%$ or shortly after."\
 "" 0 fig:peeq-srf
.SETR fig:peeq-srf
.DE

It results in a mangled caption. The maths are
reproduced, but there are lots of gibberish too.

I can upload the resulting postscript to illustrate
the problem, but perhaps this is a known issue?

Thanks

Anton


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