2022.2

Second, contamination can happen in method 1) above if a pen or paper is moved from one location to
another. Similarly to the previous contamination example, if there exists a document in the Capture
Database where the "wrong" data is processed, it will update a document where it does not belong.
Again, neither the pen nor PReS Workflow have any idea that this causes an error until it's too late.
Third, contamination (the most common one) can happen if pattern sequences get mixed up, if pens or
paper gets swapped between users, etc. For example, again using a shipping company (with example
2-A), if two of the drivers were to meet for a coffee and exchange their pens inadvertently (we hope,
anyways), the pens would be signing the "wrong" documents all day and, when docked, would update
the wrong documents in the database.
In all of these cases, the errors often do not appear when the wrong document is updated - it actually
occurs when the "right" data is processed. This happens precisely because the Pen and Production
have no idea that the wrong data is received and will generally close the document after that "wrong"
data has been processed - this often works with no error. However, when the "right" data is processed,
then it tries to update a document that has already been closed by the "wrong" data, and thus fails.
Safeguards
There are certain safeguards against contamination:
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PlanetPress Capture checks for pattern size and placement. If the data contains ink for a specific
pattern but the ink location does not correspond to the Capture Fields of the document it's updat-
ing, it will fail.
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Errors can be set to stop and revert the whole current batch. If a single error occurs during the
pen data processing, it is possible for this processing to be stopped and all changes the Capture
Database reverted. In implementations where the pen signs high number of documents, this can
especially be an easy way to do this, as chances are the data will not match in at least one case.
Conclusion
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PReS Workflow can only generate 20,000 unique patterns
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One pattern is used (locked) for each page containing a pattern.
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Processing the ink data from a pen and closing the document releases the pattern
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Most implementations will not need more than 20,000 patterns
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When necessary, patterns can be extended using multiple servers or Pattern Sequences (as long
as these are used in separate physical locations).
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It is extremely critical that contamination be avoided at all costs.
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Whenever possible, always avoid using pattern sequences unless it is absolutely necessary to
do so.
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