A few questions regarding a recent thesis by Lucy Zuberbuehler (Univ. of Bern, Fac. of Lettres, Bachelor thesis prepared under the guidance of Prof. Dr. Roland Bielmeier) are too important not to be asked. 
The author brilliantly compares the signs on a birch bark manuscript from a recently established private museum,  the Sultani Museum, in Kabul (on the basis of photographs available on the Western Himalaya Archive, Vienna), with the Indus signs as available on Indus seals etc. of ca. 2500 BCE. 

http://www.docstoc.com/docs/103016650/A-comparison-of-a-manuscript-with-indus-script---Lucy-Zuber-Buehler-(2009)

In view of the observed properties of birch bark, it would seem reasonable to exclude the possibility that we have here a piece of writing from the time of the Indus civilization (C-dates are not available). 
The folio is conserved in a box with perhaps 16th century C.E. paintings of horse riding and maybe polo playing men. 
A close analysis of the writing leads Lucy Zuberbuehler to formulate (i.a.) the following important observation: 
"The inability to locate any obvious ink failure could mean that the Kabul manuscript was written with a reservoir pen. This type of pen purportedly existed as early as the 10th century in the Islamic world" (p. 15). 
Suppose the folio is 1/2 a millennium or even, somehow, 2 millennia old (as the oldest currently available birch bark mss fragments): the gap with the Indus civilization period is in either case still enormous. 
If the signs on this folio do have a syllabic or alphabetic value and if they do represent a "living" script, their correspondence with the much older Indus signs is simply TOO exact, since in other living scripts, at least alphabetic and syllabic-alphabetic ones, significant cummulative modifications are observed every two centuries or so (unless printing intervenes). 
Did someone copy the signs (perhaps several centuries ago) from some other object without knowing what the signs represented? Did the signs fail to evolve significantly as they had a non-alphabetic and non-syllabic function also for the one who wrote the signs on the folio? Finally, can any functional continuity be accepted between the use of signs in the Indus civilization and the use of similar signs on the Kabul manuscript, around two or rather three millennia later?
Jan Houben