[GRASSLIST:4612] Tiling DRG's

[cbsled at ncia.net]

The USGS DRG's have the whole paper map in the file.
r.patch will overlay them, but since there is non-zero data on the skirt,
the effect of tiling them is exactly like laying the whole paper maps on top of each other.
How could I clip the edges of these files without losing their georeferencing?

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Carl Brown cbsled at ncia.net
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