An interrogative particle is a sign whose unique function is to indicate that an utterance is an interrogative. As wh-signs in LIS have a specific meaning (What? When? Where? etc.), they do not qualify as interrogative particles. An exception might be qartichoke. As its meaning is underspecified in absence of a disambiguating mouthing, it might be analysed as an interrogative particle, especially if mouthing is analysed as external to the core meaning of this sign.