diff --git a/ascii-art/ctt.ascii-art b/ascii-art/ctt.ascii-art
new file mode 100644
index 0000000..e9c2888
--- /dev/null
+++ b/ascii-art/ctt.ascii-art
@@ -0,0 +1,41 @@
+.--------.
+| Signer |
++--------+------------------------------------------.
+|                         .-----------.             |
+|                         |    phdr   |             |
+| .-------.   .---------. |  .-----.  |             |
+| | datum |  / SK_cose /  |  | ... |  |             |
+| '--+-+--' '----+----'   |  '-----'  |             |
+|    | |         |        '-+-+-------'             |
+|    | |         v          | |                     |
+|    | |      .-----.       | |                     |
+|    |  '--->| Sign1 |<-----' |                     |
+|    |        '-+-+-'         |                     |  .-----.
+|    |          | |           |     .----.          |  | TSA |
+|    |          |  '----------)--->| hash |         |  +-----+---------.
+|    |          |             |     '-+--'          |  |      .-.      |
+|    |          |             |       |             |  |     | L |     |
+|    |          |             |       v             |  |      '+'      |
+|    |          |             |  .----------------. |  |       |       |
+|    |          |             |  | messageImprint +-+->|       v       |
+|    |          |             |  '----------------' |  |  .---------.  |
+|    |          |             |                     |  | | timestamp | |
+|    |          |             |  .-------.          |  |  '---------'  |
+|    |          |             |  | nonce +----------+->|       ^       |
+|    |          |             |  '-------'          |  |       |       |
+|    |          |             |                     |  |   .---+----.  |
+|    |     [signature]     [phdr]                   |  |  / SK_tsa /   |
+|    |          |             |                     |  | '--------'    |
+|    |          |             | .-----------------. |  |               |
+|    |          |             | |      uhdr       | |  '-------+-------'
+|    |          |             | | .-----. .-----. | |          |
+|    |          |             | | | ... | | TST |<--+---------'
+|    |          |             | | '-----' '-----' | |
+|    |          |             | '--------+--------' |
+|    |          |             |          |          |
+'----+----------+-------------+----------+----------'
+     |          |             |          |
+ [payload]      v             v        [uhdr]
+     |        .------------------.       |
+      '------>| rfc3161-ctt COSE |<-----'
+              '------------------'
diff --git a/ascii-art/ttc.ascii-art b/ascii-art/ttc.ascii-art
new file mode 100644
index 0000000..231143d
--- /dev/null
+++ b/ascii-art/ttc.ascii-art
@@ -0,0 +1,38 @@
+.--------.                                           .-----.
+| Signer |                                           | TSA |
++--------+----------------------------------------.  +-----+---------.
+| .-------.               .----.                  |  |      .-.      |
+| | datum +------------->| hash |                 |  |     | L |     |
+| '-+---+-'               '-+--'                  |  |      '+'      |
+|   |   |                   |                     |  |       |       |
+|   |   |                   |                     |  |       v       |
+|   |   |                   v                     |  |  .---------.  |
+|   |   |                 .----------------.      |  | | timestamp | |
+|   |   |                 | messageImprint +------+->|  '---------'  |
+|   |   |                 '----------------'      |  |       ^       |
+|   |   |                                         |  |       |       |
+|   |   |                 .-------.               |  |   .---+----.  |
+|   |   |                 | nonce +---------------+->|  / SK_tsa /   |
+|   |   |                 '-------'               |  | '--------'    |
+|   |   |                                         |  '-------+-------'
+|   |   |                 .------------------.    |          |
+|   |   |                 |       phdr       |    |          |
+|   |   |     .---------. | .-----.  .-----. |    |          |
+|   |   |    / SK_cose /  | | ... |  | TST |<-----+---------'
+|   |   |   '----+----'   | '-----'  '-----' |    |
+|   |   |        |        '--+--+------------'    |
+|   |   |        v           |  |                 |
+|   |   |     .-----.        |  |                 |
+|   |    '-->| Sign1 |<-----'   |    .---------.  |
+|   |         '--+--'           |    |  uhdr   |  |
+|   |            |              |    | .-----. |  |
+|   |            |              |    | | ... | |  |
+|   |       [signature]       [phdr] | '-----' |  |
+|   |            |              |    '----+----'  |
+|   |            |              |         |       |
+'---+------------+--------------+---------+-------'
+    |            |              |         |
+ [payload]       v              v       [uhdr]
+    |          .------------------.       |
+     '-------->| rfc3161-ttc COSE |<-----'
+               '------------------'
diff --git a/draft-birkholz-cose-tsa-tst-header-parameter.md b/draft-birkholz-cose-tsa-tst-header-parameter.md
index 1779be3..1f14615 100644
--- a/draft-birkholz-cose-tsa-tst-header-parameter.md
+++ b/draft-birkholz-cose-tsa-tst-header-parameter.md
@@ -183,6 +183,23 @@ IANA is requested to add the COSE header parameters defined in {{tbl-new-hdrs}}
 
 --- back
 
+# Diagrams
+
+The diagrams in this appendix illustrate the processing flow of the modes specified in {{sec-timestamp-then-cose}} and {{sec-cose-then-timestamp}} respectively.
+
+For simplicity, only the `COSE_Sign1` processing is shown.
+Similar diagrams for `COSE_Sign` can be derived by allowing multiple `SK_cose` boxes and replacing the label `[signature]` with `[signatures]`.
+
+~~~ aasvg
+{::include ascii-art/ttc.ascii-art}
+~~~
+{: #fig-ttc artwork-align="left" title="Timestamp then COSE"}
+
+~~~ aasvg
+{::include ascii-art/ctt.ascii-art}
+~~~
+{: #fig-ctt artwork-align="left" title="COSE then Timestamp"}
+
 # Acknowledgments
 {:unnumbered}