What is TDI and why do I care? Is there a list of useful TDI functions?
TDI is the language of MDSplus. When filling out a Scope (dwscope) page (and most other programs that accept MDSplus signal names), all the form fields accept TDI expressions, allowing simple arithmetic with signals, as well as function calls for more complex operations. The first argument to the MDSvalue routine is a TDI expression; knowing a bit of TDI can provide extra capabilities here as well. Perhaps the most important use is within nodes in MDSplus trees, where higher level nodes can be defined in terms of functions of raw data nodes and calibration operations, with the result then calculated for each data access. In this way all the “magic numbers” reside with the data, preventing a situation where a user is calling an incorrect calibration routine in his own program.
