Parsing Ordinals Transaction, engraved data part

Ordinals I am interested in the raw hexadecimal format of the transaction. The example transaction I use is TXID: 6fb976ab49dcec017f1e201e84395983204ae1a7c2abf7ced0a85d692e442799. There is something in the witness section of this transaction data that I don’t understand.

"5503" # 853 bytes
"20" # 20 bytes
"4a3ca2cf35f7902df1215f823d977df1174048b062e03a44f71c2ee736a60cc5" # (A)
"ac" # OP_CHECKSIG
"00" # OP_FALSE 
"63" # OP_IF
"03" # 3 bytes
"6f7264" # "ord"
"0101" # N/A N/A
"09" # 9 bytes
"696d6167652f706e67" # "image/png"
"00" # OP_FALSE
"4d" # OP_PUSHDATA2
"0802" # 520 bytes => maximum value
<skipping the following 520 bytes of image data>
"4d" # OP_PUSHDATA2
"1101" # 273 bytes
<skipping the following 273 bytes of the rest of the image data>
"68" # OP_ENDIF
"21" # 33 bytes
"c04a3ca2cf35f7902df1215f823d977df1174048b062e03a44f71c2ee736a60cc5" # (B)
"00000000" # locktime & end of entire transaction data

Can someone tell me what (A) and (B) stand for?