Could you explain each variable regarding ACI_Gatt API for BLE read/write data?

[KKIM.6]

I'm making BLE data read and write a program but several functions are unclear.

Because there is an only one example regarding "ACI_Gatt_Update", I have difficulty understanding read and write gatt listed like the figure.

what's the

"Connection_Handle"

"Attr_Handle"

?

[KKIM.6]

if there is an eample for aci_gatt_write and aci_gatt_read, please let me know.