Setting crescendoSpanner

[Cameron Horsburgh]

Hi folks,

I'm like I'm missing something obvious here, but I don't seem to be able 
to find the answer.

I want to use cresc. and decresc. symbols without the spanner defining 
it's extent. By default the spanner is printed as a dashed line.

The docs tell me that this can be changed by setting crescendoSpanner. 
However, in the internals doc all I can find are these options:

(crescendoSpanner ,symbol? "Type of spanner to be used for crescendi.
One of: @samp{hairpin}, @samp{line}, @samp{dashed-line},
@samp{dotted-line}.  If unset, hairpin type is used.")

What do I use to get no spanner at all?

--Cam