Lawyers are sometimes asked to render an opinion that "the [bill of sale] is sufficient as to form to transfer the Company’s right, title and interest in and to the assets specified in the Agreement to the Buyer".   Implicit in this opinion request is an assumption that a bill of sale must conform to some specific form.  That assumption, however, is at odds with Section 1052 of the California Civil Code which provides: "A transfer may be made without writing, in every case in which a writing is not expressly required by statute".  As the Court of Appeal has explained:

An assignment requires very little by way of formalities and is essentially free from substantive restrictions. "[I]n the absence of [a] statute or a contract provision to the contrary, there are no prescribed formalities that must be observed to make an effective assignment. It is sufficient if the assignor has, in some fashion, manifested an intention to make a present transfer of his rights to the assignee." (9 Corbin on Contracts (rev. ed. 2007) § 47.7, pp. 147-148; see Rest.2d Contracts, §§ 317, 324.)

Amalgamated Transit Union, Local 1756, AFL-CIO v. Superior Court, 46 Cal. 4th 993, 1002, 95 Cal. Rptr. 3d 605, 209 P.3d 937 (2009). 

Some statutes do impose substantive requirements of assignments.  Most notably, perhaps, Section 1091 of the Civil Code provides: “An estate in real property, other than an estate at will or for a term not exceeding one year, can be transferred only by operation of law, or by an instrument in writing, subscribed by the party disposing of the same, or by his agent thereunto authorized by writing.”