Blue peter and Code flag

Blue peter noun - A blue flag with a white square in the center indicates that the vessel is ready to sail.

Code flag and blue peter are semantically related. In some cases you can use "Code flag" instead a noun phrase "Blue peter".

Code flag noun - One of an international code of flag signals used between ships.

Blue peter and code flag are semantically related. Sometimes you can replace phrase "Blue peter" with "Code flag", this phrases are similar.