Bava Batra

an erasure [however] is inadmissible  although it had been confirmed.  [The law,] however, [that] an erasure invalid only applies  [to the case where it occurs] in the position [of the formula] 'firm and established'  and [occupies the] same space as 'firm and established'. According to R. Jeremiah b. Abba, however, who stated, '[On] the back of the writing and corresponding to [all] the written part, on the external [side of the deed]',  is [there no cause] to apprehend that he might write on the inside  whatever he wished and induce additional witnesses to sign on the outside;  and might say, 'I did it  in order to increase the number of witnesses'?  — He  replied to him:  Do you think [that] witnesses  sign in the [same] order [as the lines of the deed],  they sign [vertically] from bottom to top?  But is [there no reason] to apprehend [that some] unfavourable condition might occur in the last line [of the deed] and he would cut off that last line, and [though] with it he would [also] cut off [the name of the witness] 'Reuben',  [the deed] would [yet] remain valid through [the remaining part of the signature], 'son of Jacob witness';  as we learnt: [The signature]. 'son of X, witness', is valid?  — [The witness] writes, 'Reuben son of', across one line,  and, 'Jacob. witness', above it.  Is [there no reason, however,] to apprehend that [though] he might cut off, 'Reuben son of', [the deed] would [yet] remain valid through [the remaining portion of the signatures]. 'Jacob, witness';  as we learnt: [a signature], 'X, witness' is valid?  — [The word], 'witness' is not written.  And if you wish it may be said [that a witness], in fact, does write [after his signature], 'witness', [but this is a case] where it is known that the signature