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'IMAGE_'yyyyMMdd_HHmmss'.jpg' This will overrule the observation time stored in the file, some grid formats don't contain the time at all, so for these files the pattern is required. Put the literal parts of the pattern between single quotes. If the litteral parts contain unrelated numbers or an unrelated date, replace each digit with a ?. The ? should still be between the single quotes.
Example: T20190524_20190722 → 'T????????_'yyyyMMdd.
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'IMAGE_'yyyyMMdd_HHmmss'.jpg' This will overrule the forecast time stored in the file, some grid formats don't contain the forecast time at all, so for these files the pattern is required. Put the literal parts of the pattern between single quotes. When the file name also contains non forecast date times. Put this parts between ' and use ? wildcard. All forecast with the same forecast time belong to the same forecast, the "fileNameObservationDateTimePattern" is not required in that case.
Example: MSPM_<observation date time>_<forecast date time>.asc → 'MSPM_??????????????_'yyyyMMddHHmmss'.asc'
When filename starts with the pattern do not use quotes in at the start: yyyyMMdd'_bla.nc'
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