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<p class=MsoNormal><font size=3 face="Times New Roman"><span lang=EN-GB
style='font-size:12.0pt'>I don't know what to do!<br>
<br>
So I send an image of my GRASS shell with the error message.<br>
<br>
Thanks so far!<br>
<br>
<br>
<br>
<br>
Old message:<br>
<br>
Dear GRASS users,<br>
<br>
I'm working with a vector map with an attribute table. I'm using the GRASS
tools with QGIS.<br>
I added a new column to my table and I don't know why my 'start editing'
buttons aren't activ. <br>
I'd like to get those new values by calculating the difference of 2 other
existing columns.<br>
<br>
Do you know any solution for that?<br>
<br>
Further I thought about doing the calculation within the GRASS shell but I
don't know what tool I should use and how. for example the db.execute, but I
couldn't find any calculation possibility in it.<br>
<br>
</span>thanks,<br>
stef</font><font size=2 face=Arial><span style='font-size:10.0pt;font-family:
Arial'><o:p></o:p></span></font></p>
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