23. A computing environment comprising a processor, the computing environment being configured to execute a user interface for training a natural language understanding (NLU) system that has one or more models, the user interface comprising: a first portion displaying a model display representative of the one or more models; a second portion displaying unannotated training inputs; one or more user-actuable inputs configured to be actuable by a user to indicate a user-selected one of the unannotated training inputs, the computing environment comprising a processor that is configured to receive the user-selected unannotated training inputs and provide an output comprising a plurality of proposed annotations for the user-selected unannotated training inputs; a third portion displaying the proposed annotations for a selected one of the unannotated training inputs; a fourth portion displaying a sample of the unannotated training input not covered by the proposed annotations; one or more user-actuable inputs configured to be actuable by a user to indicate a user-selected segment of the sample not covered, such that the input indicating the user-selected segment is received by the processor; a fifth portion displaying a plurality of alternative proposed annotations for the user-selected segment, provided by the processor in response to the input indicating the user-selected segment; and a sixth portion displaying an indication of a volume of training data used to train a plurality of different portions of the one or more models of the natural language understanding system; such that the fifth portion displaying the plurality of alternative proposed annotations further includes: displaying one or more user actuable alternative annotation node inputs; displaying a user actuable delete node input which, when actuated, deletes a child node; displaying a user actuable add node input which, when actuated, adds a child node; displaying a plurality of alternative proposed annotations to data portions associated with a child node in response to that child node being deleted; and enabling the user to select one of the alternative proposed annotations from among the plurality of alternative proposed annotations, and using the user-selected alternative proposed annotation for training the natural language understanding (NLU) system.
23. A computing environment comprising a processor, the computing environment being configured to execute a user interface for training a natural language understanding (NLU) system that has one or more models, the user interface comprising: a first portion displaying a model display representative of the one or more models; a second portion displaying unannotated training inputs; one or more user-actuable inputs configured to be actuable by a user to indicate a user-selected one of the unannotated training inputs, the computing environment comprising a processor that is configured to receive the user-selected unannotated training inputs and provide an output comprising a plurality of proposed annotations for the user-selected unannotated training inputs; a third portion displaying the proposed annotations for a selected one of the unannotated training inputs; a fourth portion displaying a sample of the unannotated training input not covered by the proposed annotations; one or more user-actuable inputs configured to be actuable by a user to indicate a user-selected segment of the sample not covered, such that the input indicating the user-selected segment is received by the processor; a fifth portion displaying a plurality of alternative proposed annotations for the user-selected segment, provided by the processor in response to the input indicating the user-selected segment; and a sixth portion displaying an indication of a volume of training data used to train a plurality of different portions of the one or more models of the natural language understanding system; such that the fifth portion displaying the plurality of alternative proposed annotations further includes: displaying one or more user actuable alternative annotation node inputs; displaying a user actuable delete node input which, when actuated, deletes a child node; displaying a user actuable add node input which, when actuated, adds a child node; displaying a plurality of alternative proposed annotations to data portions associated with a child node in response to that child node being deleted; and enabling the user to select one of the alternative proposed annotations from among the plurality of alternative proposed annotations, and using the user-selected alternative proposed annotation for training the natural language understanding (NLU) system. 28. The computing environment of claim 23 wherein the first portion displays the model display in the form of a dependency structure having parent and child nodes.