ISO7731: May I have some question regarding TI some document mention ISO7731?

Tool/software:

Dear SIR:

May I have some question regarding TI some  document mention ISO7731?

as below link page 4 Figure 5 circuit have mention BAS40 on pin 5 and D2 between pin 12 and 13 

https://www.ti.com/lit/an/slyt403a/slyt403a.pdf?ts=1744855395371&ref_url=https%253A%252F%252Fwww.google.com%252F

Would you have more information regarding  page 4 Figure 5 circuit have mention BAS40 on pin 5 and D2 between pin 12 and 13 .

Q1)The D2 the same pin 5 part is BAS40 ,too? or,...

Q2)What's function regarding the BAS40 on pin 5 and D2 between pin 12 and 13 ?

      (Is the D2 for Prevent signal flow from SDA1 to SDA2 ? 

       and  Is the BAS40 on pin5 for Prevent signal flow from SDA2 to SDA1?)

thanks