Ngspice and ngnutmeg data is in the form of vectors: time, voltage, etc. Each vector has a type, and vectors can be operated on and combined algebraically in ways consistent with their types. Vectors are normally created as a result of a transient or dc simulation. They are also established when a data file is read in (see the load command 17.5.40), or they are created with the let command 17.5.37 inside a script. If a variable x is assigned something of the form $&word, then word has to be a vector, and the numeric value of word is transferred into the variable x.