Documentation:dt window - MdsWiki
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Window Data Type

MDSplus provides a window data type which is used exclusively in conjunction with a dimension data item. The window provides a means for bracketing a potentially infinite vector of values generated by a range data item. A window data type is a structure containing three fields: the start index, the end index and the value at index 0. The window brackets the axis portion of a dimension item by finding the nearest element in the axis to the "value at index 0" value. The subset of the axis elements are selected using the start index and end index using this starting element as the index 0. For example if the window was BUILD_WINDOW(-5,10,42.), MDSplus would find the element in the axis portion of the dimension closest to a value of 42 (assuming the axis is always increasing) and call that element, element number 0. The subset would be this element and the 5 elements before it and the 10 elements after it. For a more detailed explanation see the description of the dimension data type.

The following table lists some of the functions available for creating or accessing windows:

Function Description
BEGIN_OF Return begin portion of a window
BUILD_WINDOW Build a window structure
END_OF Return the end portion of a window structure
MAKE_WINDOW Make a window structure