My question is about Enigma rotors I found this explanation of Enigma rotor movement on this website, but can't quite understand the methodology: Enigma rotation example

A ⤑ B → D ⤑ C (rotor III in position B)
C ⤑ C → D ⤑ D (rotor II in position A)
D ⤑ D → F ⤑ F (rotor I in position A)
F ↔ S (reflector B)
S ⤑ S → S ⤑ S (rotor I in position A, reverse)
S ⤑ S → E ⤑ E (rotor II in position A, reverse)
E ⤑ F → C ⤑ B (rotor III in position B, reverse)

I follow steps 2 to 6 inclusive OK, but unsure about steps 1 &amp; 7:
I understand that the rotor moves before encryption, so I get the A&gt;B&gt;D, but why the final D&gt;C? and similarly the end of step 7.  I can't understand where that final step comes from.
I guess there is a similar bit of complexity when the the rotors cause the next one to step ahead when the notches engage?
I'm only doing this for interest, as I used to use AES a lot in my job (now retired), encrypting electronic messages, so thought I'd get my head round Enigma to keep the brain ticking over.
Think I understand now (correct me if I'm wrong)!:
Because the rotor has advanced, pressing A goes into rotor III at letter B, which encodes to D, but &quot;comes out&quot; in &quot;position&quot; C because the rotor has advanced.
I created a spreadsheet &quot;picture&quot; which explained to me how the encoding &amp; wiring works to encrypt the letter 'A' twice, starting with all 3 rotors in the 'A' position.