[gradsusr] underscore in variable name

[Becker, Bernd]

dear all, 

Running opengrads on linux redhat6:
(Linux/Versions/2.0.1.oga.1/x86_64/grads)

I learn about "forbidden" characters in variable names:

ga-> define obs_t=ave(((tmax+tmin)/2.),t=1,t=32)
DEFINE error:  Name too long; missing '='

whereas

ga-> define obs=ave(((tmax+tmin)/2.),t=1,t=32)  
Averaging.  dim = 3, start = 1, end = 32

works!

Dot is an obvious candidate, but _ underscore?
which other characters are forbidden in variable names?

Cheers,
Bernd.


--
Bernd Becker   Climate Impacts Product Development
Met Office Hadley Centre    FitzRoy Road  Exeter   Devon EX1 3PB  United
Kingdom
Tel.: +44 (0) 1392 884511 Fax: +44 (0)870 900 5050
E-mail:bernd.becker at metoffice.gov.uk -
http://www.metoffice.gov.uk/research/our-scientists/seasonal-to-decadal/
bernd-becker
http://www.metoffice.gov.uk/news/releases/archive/2011/weather-game