Relevant postpositions: -이고 (-iko), -이라 (-ila), -이라고 (-ilako)
Korean quotative markers identify direct and indirect quotes as well as reported speech. These postpositions mark that participant arguments of the verbs of communication (e.g., saying, telling) and of cogitation (e.g., thinking and considering).
Quotatives that mark the content of communication or cogitation is labelled with the Content label. Unlike Topic that marks the subject matter of communication/cogitation, the quotative postpositions mark the content of the information that is evidenced by the speaker or writer.
'He lied by saying '[I am] single'. Lit: He said lie 'single'.' 003
'He thinks that Chengcu is a beautiful town.' 004
For verbs of considering (e.g., consider, deem, acknowledge) or designation (e.g., call, name), we assign Identity↝Content to the postposition that mediates a relationship between an entity and an identity (e.g., entity's identity, profession, name, label).
'Do you know the person who is called Korea's Bill Gates?' 008
There is a slightly more idiomatic usage where the nominal marked is interpreted as a claim that does not meet up to the speaker/writer expectation of the label. This usage encodes a level of indignation on the part of the speaker.
'Do you consider that a joke? (You calling that a joke?)' 009