Where did you find "word is using shift" in the rules?

In the standard Vigenere cipher, you're using the ciphers that are shifted by one character when you go down the cipher tableu. This is illustrated in the rules. One of the required modifications is that this character shift is based on the position of the word to be encrypted inside it's sentence. Thus the first word's cipher tableau starts with
Code:

ABC...
BCD...
CDE...


In case of the second word, the shift would now be two characters, thus
Code:

ABCDEF...
CDEFGH...
EFGHIJ...


In effect each word inside a sentence to be encrypted is using it's own distinct cipher tableau.
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There are two types of vessels, submarines and targets.