https://doi.org/10.1351/goldbook.H02885
Compounds derived from oxoacids $\ce{R_{k}E(=O)_{l}(OH)_{m}}$ ($l \neq 0$) by replacing a double-bonded oxygen atom by $\ce{=NNR2}$, as in carbohydrazonic acids, $\ce{RC(OH)=NNH2}$ and sulfonohydrazonic acids, $\ce{RS(=O)(=NNH2)OH}$.