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  • Date and time last "touched"

    "Date/time last touched" values may or may not be useful information.

    The metadata for each layer in our GIS library displays three "Date/time last touched" values, one each for the Shapefile, Enterprise Geodatabase, and Coverage layer formats kept in our GIS Library. One format is the designated "Maintenance Format" as specified in the "Maintenance format in our library" field.

    The touched date/time is the most recent date time found on the files (or the date loaded in the case of Enterprise GDB format) for each layer format.

    The "touched" date and time may or may not represent a meaningful update to the data content. It means that something was done to the files on that date, but we don't know what.

    The touched date may change as a result of:

    • Update to the layer's content
    • Certain file maintenance
    • Reprocessing, re-saving or replacement with the same data.
    • ... or any number of things we can't inclusively list here.

    There are even programs that will do nothing but "touch" files with the sole purpose of changing the file's date and time and doing nothing else. We don't routinely use such programs.

    "Date/time last touched" may be a good indicator of a recent data content update provided it's evaluated in context and makes sense. However, there is no way to be sure there was a meaningful content update on this date. On the other hand, we can be rather certain that a layer has not been updated since the touched date. That is, we know the last update was on or before the touched date and it hasn't been updated since.

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