The dc|ac|tran specifies the analysis type for which the measurement is active. The result is a token, starting with a letter, which will be used to uniquely identify the results of the measurement. A vector with this name will be added to the current plot, if the measurement is successful.
The rest of the line can have various formats. The next part of the statement is either an interval specification, or a single point specification.
There is a second form available, as shown above. In this case, after all interval and point measurements have been performed, the expression will be evaluated and the result saved in result. The expression can reference other measurement results in addition to the usual vectors and functions provided by the system. These measurement lines are evaluated in the order found in the input.
In .measure lines, single-quote marks or parentheses can be used to delimit complicated expressions. The usual single-quoted expression expansion performed when input is sourced is not applied to .measure> lines. Instead, internally, the single quotes are replaced by parentheses, preventing expression expansion but allowing parameter substitution, which is performed at the same time.
Vector names found in .measure lines are added to the internal save list, guaranteeing that the necessary data will be available when needed, whether or not the vector has been mentioned in a .save line.