(a)__Is mathematically derived from or related to the other digits of the file number; and

(b)__Aids the filing office in determining whether a number communicated as the file number includes a single-digit or transpositional error.

(3)__Except as otherwise provided in subsections (4) and (5), the filing office shall:

(a)__Index an initial financing statement according to the name of the debtor and index all filed records relating to the initial financing statement in a manner that associates with one another an initial financing statement and all filed records relating to the initial financing statement; and

(b)__Index a record that provides a name of a debtor that was not previously provided in the financing statement to which the record relates also according to the name that was not previously provided.

(4)__If a financing statement is filed as a fixture filing or covers as-extracted collateral or timber to be cut, it must be filed and the filing office shall index it:

(a)__Under the names of the debtor and of each owner of record shown on the financing statement as if they were the mortgagors under a mortgage of the real property described; and

(b)__To the extent that the law of this State provides for indexing of records of mortgages under the name of the mortgagee, under the name of the secured party as if the secured party were the mortgagee thereunder, or, if indexing is by description, as if the financing statement were a record of a mortgage of the real property described.

(5)__If a financing statement is filed as a fixture filing or covers as-extracted collateral or timber to be cut, the filing office shall index an assignment filed under section 9-1514, subsection (1) or an amendment filed under section 9-1514, subsection (2):

(a)__Under the name of the assignor as grantor; and