The label of a labeled statement is the identifying word. It must be fully capitalized in braille regardless of the print style used. It doesn't matter if the following text is in regular or non-regular type.
Even though it is not specified in the Code, it is recommended that a labeled statement follow the format for formal proofs. A labeled statement would thus be preceded and followed by a blank line. If there are two Postulates in a row in print, there would be a blank line between them.
Rule V §33 gives examples of labels used in labeled statements, including "postulate". But if the label of the statement is expanded, it is still the label. You would follow the same guidelines as for that of a one word label.
Does that help? Let me know if I've been too vague. Dorothy