A data selection widget is opened for a stream when the selected axis item requires further user input. However, if the NOTRACE option is de-selected (the default), such a selection widget will not be activated for the `x'-stream, which will be assigned the selection of the `y'-stream.
In the data selection widget, input beam, output beam, and triple have to be specified, depending on the selected axis item. The selection for channels, baselines, and points are for this input, output beam, or triple only. The ALL OB option is valid only for uv-coverage plots, where it implies that the data of all output beams, channels, and baselines shall be plotted.
A data selection for a specific index (e.g. channel) is made by combining a directive (ALL, NEXT, CURRENT, PREVIOUS, SELECTED) with a selection typed into the selection line. A selection line entry is a series of numbers separated by commas, and/or number ranges consisting of a lower and upper value separated by a dash. This entry is parsed into a vector of selected index values (e.g., `2,3,6-9' is parsed into `2,3,6,7,8,9'). Please do not forget to hit return after typing in your selection line entry!
NEXT and PREVIOUS return a selection of the next or previous index values, where is the number of selected index values in the selection line. Thus, if the selection line reads `1,2', NEXT will select `3,4' for the next plot, then `5,6' and so on. It is not recommended to select these directives for more than one axis at a time as they will act simultaneously. The CURRENT directive simply leaves the current selection unchanged (which is not necessarily identical to the displayed selection!).
It is not necessary to specify indices or alter the corresponding selection for axis items which do not contain those indices.
The pt and star selection address the same index. Therefore, the star selection is applied after the pt selection as displayed in the data selection widget. When plotting scan data, you can obtain information on which scans correspond to given stars from the UTILITIESLISTSCANS button.