Each of the napkins but one contains a drawing that is based on ASCII art from one of the RFCs (Requests for Comments), which are collectively the standards documents of the Internet. RFCs are hinted by the SHOULD in the title, which is a phrasing and formatting used in RFCs; and "paints a picture with each character" hints at ASCII art. The original ASCII art is replicated below.
The one napkin that is not from an RFC is the one with six rows and four columns, with the left columns labeled "Input" and the right columns labeled "Output". This napkin clues the extraction mechanism. First you identify the RFCs the other figures are from and then order by RFC number. Convert the last two digits of each RFC number to letters (01 = A, etc.) in this order and they spell the answer, AUTUMN.
RFC 1001:
====+=========+=====BROADCAST AREA=====+==========+=========+====
| | | | |
| | | | |
+--+--+ +--+--+ +--+--+ +--+--+ +--+--+
| B | | B | | B | | B | | B |
+-----+ +-----+ +-----+ +-----+ +-----+
RFC 2321:
comb neck body feet
| | | |
v v V V
,^/'/, ,______________________. ,
i' ' / / =========<-
/ <o> `---------/ \ `
.;__. ,__,--------. / ,
/ ,/ vv \ =========<-
'-' `-----------------------' `
^ ^ ^
| | |
beak wattles legs
RFC 2420:
P1 P2 Pi
| | |
IV--->(X) +------>(X) +-------->(X)
v | v | v
+-----+ | +-----+ | +-----+
k1->| E | | k1->| E | : k1->| E |
+-----+ | +-----+ : +-----+
| | | : |
v | v : v
+-----+ ^ +-----+ ^ +-----+
k2->| D | | k2->| D | | k2->| D |
+-----+ | +-----+ | +-----+
| | | | |
v | v | v
+-----+ | +-----+ | +-----+
k3->| E | | k3->| E | | k3->| E |
+-----+ | +-----+ | +-----+
| | | | |
+---->+ +------>+ +---->
| | |
C1 C2 Ci
(Note that this is not RFC 2451, due to the fact that there are not
enough arrows on the vertical lines.)RFC 3821: |----------------Bit--------------------| | | | 0 1 2 3 4 5 6 7 | +----+-----------------------------+----+ | Ch | Reserved | SF | +----+-----------------------------+----+(Note that this is not RFC 2529 or RFC 2893, due to the lack of extra vertical bars in the second row.)
RFC 4213: +-------+-------+-------+-------+-------+-------+------+------+ | FE 80 00 00 00 00 00 00 | +-------+-------+-------+-------+-------+-------+------+------+ | 00 00 00 00 | IPv4 Address | +-------+-------+-------+-------+-------+-------+------+------+
RFC 4814:
|--------------------<----------------------|
| |1
_______ __|__ _____ _____ _____ __|__
| | 1 | | 1 | | 1 | | 1 | | 1 | |
| start |--->| 1 |--->| 2 |--->| 3 |--->| 4 |--->| 5 |
|_______| |_____| |_____| |_____| |_____| |_____|
| | | | | | |
| |0 |0 |0 |0 |0 |0
|-<-|----<----|----<-----|----<-----|----<-----|----<-----|