We list here all available procedures for the HDS access. Italic names, e.g. value, have to be replaced with variable names; they will be allocated automatically and return the data requested. If a type is specified, e.g. value_double, the variable must be declared and initialized before. Optional arguments are in square brackets, e.g. status; if several optional arguments are listed, only one can be selected as such and arguments to the left then are compulsory! Please refer to the HDS manual for explanations on the individual commands.