Dave Newt and I (Mark Brader) write:
... orientation-information is much better in Paris generally. Almost
wherever you are in the central area, you'll find one of those
billboards with a Plan du Quartier on it.

Which extends as far as the nearest arrondissement boundary. And since
arrondissements are bounded by main streets, which is where you probably
are, there is an excellent chance that you're standing at the edge of
the map, and whatever's just off the other side of the street isn't shown.
Good idea, but not the best implementation.

Is that true? To be honest, I can't remember for sure, but don't the
maps show the edges of the surtrounding arrondissements, but slightly
greyed out? ...

I remember it because it seemed a distinctively silly way of doing it.
I can't find any maps on the Web that are the same as the ones posted
on main streets, but these maps on two arrondissments' official web
sites are somewhat similar (and show that arrondissments seem to find
this a sensible style of map):

http://admin.mairie7.paris.fr/mairie...que/carte7.gif
http://www.mairie13.paris.fr/mairie1...e/carte13e.jpg

I have a feeling this is the case, as I don't remember ever encountering
this problem (and I lived right on the boundary of two arrondissements,
and used the maps around my flat an awful lot.

Well, there are some cases where two or three arrondissements have gone
together to produce a single map showing all of them. If you were on one
of the boundaries where two such arrondissements meet, you'd be okay.
This still doesn't help if you're at the boundary of the combined map.
If the 5th and 6th are on the same map near the 5th/6th boundary, say,
then the maps near the 4th/5th boundary would also show the 5th and 5th.

In fact, even if what you say is correct, then what I was saying before
still holds true - there are so many of those maps around the junctions
that you rarely have to walk more than a couple of minutes to find the
next one.

Yes, if you're at the boundary it's typically just across the street.
It's not a *major* annoyance, just an annoyance.
--
Mark Brader, Toronto "To great evils we submit; we resent
little provocations." -- W. Hazlitt, 1822

My text in this article is in the public domain.