Within the [ActiveState] [ActiveTcl] [base-tcl] [tclkit]-like stand-alone interpreter is a package called '''trsync'''.

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[A delta virtual filesystem] appears to be related in some way to trsync. 
Delta calculation for the template framework and filesystem based on vfs by Stephen Huntley.

[[more info on how to use this?]]

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[LV] ActiveTcl SPARC Solaris patchlevel 8.6b1.1 - provided as a ActiveTcl 8.6 beta back in the good old days.
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% package require trsync
couldn't read file "/tmp/.lwv/ActiveTcl-8.6.0/bin/base-tcl8.6-thread-solaris-sparc-2.8/lib/vfs/template/tdelta.tcl": no such file or directory
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I don't have a currently supported platform on which to test this. 

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%| [Category package] |%
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