This registry entry is by PC-DMIS internally to store the value for the last used paper size for custom reports. The paper size is contained in a string of numbers that looks something like this: "255;2354;3223;926;1268;1;0".
Each value is separated by a semi-colon character (;) and is based off of printer properties. From left to right, the seven numbers in the string represent the following:
paperSizeID - internal ID of the paper size
paperSize.x - width
paperSize.y - height
sizeScroll.x - scroll width
sizeScroll.y - scroll height
scroll indication - should always be 1
Landscape - 0 for portrait, 1 for landscape
Generally, you shouldn't modify this registry entry.
Entry Name: CustomReportLastUsedPaperSize
Entry Type: String value containing seven numbers separated by semi colon characters.