1. In a mapping tool graphical user interface, a method of creating a mapping, comprising: displaying a graphical representation of a source object including a source tree structure comprising at least a source root node, a source record node, and a source field node in a source screen region; displaying a graphical representation of a target object including a target tree structure comprising at least a target root node, a target record node, and a target field node in a target screen region; creating a mapping between the graphical representation of the source object and the graphical representation of the target object in a mapping screen region located between the source and target screen regions using graphical mapping indicia; indenting the source field nodes toward the target field nodes in the mapping screen region in hierarchical fashion from the source record nodes; indenting the target field nodes toward the source field nodes in the mapping screen region in hierarchical fashion from the target record nodes; indenting the source record nodes toward the target record nodes in the mapping screen region in hierarchical fashion from the source root nodes; indenting the target record nodes toward the source record nodes in the mapping screen region in hierarchical fashion from the target root nodes; replacing at least one of the source object or the target object with at least one of a modified source object or a modified target object, respectively; re-establishing at least a portion of the mapping associated with at least one of the graphical representation of the source object or the graphical representation of the target object with at least one of a displayed graphical representation of the modified source object or a displayed graphical representation of the modified target object, correspondingly, using node name association based at least in part on a node name of at least one of a modified source field node, a modified source record node, a modified target field node, or a modified target record node, of the at least one of the modified source object or the modified target object, respectively, corresponding to a respective node name of at least one of a source field node, a source record node, a target field node, or a target record node, of the at least one of the source object or the target object, respectively; and displaying indicia indicating a portion of the mapping associated with at least one of the graphical representation of the source object or the graphical representation of the target object that is not re-established after replacing the at least one of the source object or the target object with the at least one of the modified source object or the modified target object.