Slit weaving is very common in Turkish and Iranian kelims. Alternatively, weft threads of adjoining colors may link around a warp thread to avoid slits, but then creating "fuzzy" vertical lines.
The patterns of the kelims - like that of the Iban skirt - avoid long vertical lines, which weaken the textile.
Admittedly, these kelims are seldom as finely woven as the piece illustrated. Senneh kelims are perhaps the finest slit kelim weaves, as this example shows (199 x 124 cm):
http://www.rippon-boswell-wiesbaden.de/ ... 0/ZV63.jpg
The Senneh women have no difficulty creating precise and symmetrical designs. I attribute this, however, to their use of a vertical loom with tightly stretched warps. Do/did the Iban women use backstrap looms, as I saw illustrated? If so, that makes their achievement even more remarkable.
Delightful piece, Larry