In certain domains loss of life may occur if data is altered/corrupted in

Suppose you write an XSLT program which transforms this:

<alt>12000 feet</alt>

to this:

<altitude>12000 feet</altitude>

How do you ensure that the data -- 12000 feet -- was not altered/corrupted

What does altered refer to? If you make sure the XSLT copies the `alt`
element's content to the result `altitude` element you can do that with e.g.

What does "corrupted" refer to? That file IO fails to properly create
the transformation result? Do you expect to catch such errors with XSLT?

For (processing/validation) pipelines (outside the system failure scope)
you can use XProc or XSpec, I would think, to test the value in some
result (step) is the same as the value in (some/the) input step.