As stated above, bond issuances (especially public issuances) often carry a credit rating from an external credit rating agency. Many investors will, for regulatory, capital adequacy or policy reasons only be able to invest in rated instruments. A credit rating is used as a tool during the marketing of the bond to investors.
Typically, each rating agency would also publish a 'pre-sale report', setting out its rating rationale for the PPP Project and assigning a provisional rating (denoted by a "[P]" in front of the rating). Information from the pre-sale report will typically be used to facilitate the roadshow phase. A definitive rating is typically assigned once the bonds have been issued and following the agency's review of final documentation.