Front Matter: Volume 13594

A unique citation identifier (CID) number is assigned to each article in the Proceedings of SPIE at the time of publication.Utilization of CIDs allows articles to be fully citable as soon as they are published online, and connects the same identifier to all online and print versions of the publication.SPIE uses a seven-digit CID article numbering system structured as follows: The first five digits correspond to the SPIE volume number. The last two digits indicate publication order within the volume using a Base 36 numbering system employing both numerals and letters.These two-number sets start with 00, 01, 02, 03, 04, 05, 06, 07, 08, 09, 0A, 0B 0Z, followed by 10-1Z, 20-2Z, etc.