Item: D-Code list
Layout data in outdated Gerber RS-274D standard format require a separate D-code list. This list contains information about the geometric shape (circles, rectangles, circular rings are common) and the size of the aperture.
We recommend using the Extended Gerber Format (RS-274X), where the D-Code list is stored in the header of each record. This facilitates automatic processing and prevents loss of information during data transfer.