The release date field in a purchase requisition (PR) is used to calculate the date by which the PR needs to be released in order for the material to be available by the required date, taking into account goods receipt processing time, planned delivery time, and purchasing department processing time. It is not the actual date the PR was released. The questioner was confused about this and calculated the release date incorrectly by subtracting the goods receipt processing time from the required date instead of the delivery date.