The Meaning of Assignable

From time to time, I have received standby letters of credit and/or demand guarantees (collectively undertakings) or applications requesting the issuance of an undertaking indicating that it is or should be “assignable” or with wording that: “This (insert undertaking type) may be assigned”. Thesaurus resources indicate that the strongest synonyms for the word “assignable” are “debatable” and “transferable”. This begs the question, what is the intended meaning of the term “assignable” by: a) the party requesting an issuance; and b) the party issuing the undertaking when the term is included?