A user interface displayed on a user display for building a formulated query to search a database of structural data organized by classes, attributes of classes, literals of attributes, and structural relations between classes, and for displaying results of the formulated query, the user interface comprising: a structural query section to define constraints for the formulated query, the structural query section including one or more query elements to be populated, query elements being construction blocks of the query, and a means for adding one or more additional query elements comprising multiple connectors used to create a "contains" relation between a query element and one or more additional query elements, wherein one of the connectors is a first selectable element connector extending from the top of the query element which places the query element in a subordinate position to an additional query element on top, requiring the query element to be contained within the additional query element, and wherein another one of the connectors is a second selectable element connector extending from the bottom of the query element which places the query element in a superior position relative to another additional query element on the bottom, requiring the additional query element to be contained within the query element and wherein the user selects one of the connectors extending from the query element to add the additional query element in association with the query element; and a query results section for displaying results of the formulated query after the formulated query is executed, wherein each query element has a class portion which is populated by designating one of a special class identifier and a concrete class identifier, wherein the class portion is populated by designating the special class identifier or the concrete class identifier from an offered list, the user interface further including an offer section which displays the offered list. a structural query section to define constraints for the formulated query, the structural query section including one or more query elements to be populated, query elements being construction blocks of the query, and a means for adding one or more additional query elements comprising multiple connectors used to create a "contains" relation between a query element and one or more additional query elements, wherein one of the connectors is a first selectable element connector extending from the top of the query element which places the query element in a subordinate position to an additional query element on top, requiring the query element to be contained within the additional query element, and wherein another one of the connectors is a second selectable element connector extending from the bottom of the query element which places the query element in a superior position relative to another additional query element on the bottom, requiring the additional query element to be contained within the query element and wherein the user selects one of the connectors extending from the query element to add the additional query element in association with the query element; and one or more query elements to be populated, query elements being construction blocks of the query, and a means for adding one or more additional query elements comprising multiple connectors used to create a "contains" relation between a query element and one or more additional query elements, wherein one of the connectors is a first selectable element connector extending from the top of the query element which places the query element in a subordinate position to an additional query element on top, requiring the query element to be contained within the additional query element, and wherein another one of the connectors is a second selectable element connector extending from the bottom of the query element which places the query element in a superior position relative to another additional query element on the bottom, requiring the additional query element to be contained within the query element and wherein the user selects one of the connectors extending from the query element to add the additional query element in association with the query element; and a query results section for displaying results of the formulated query after the formulated query is executed, wherein each query element has a class portion which is populated by designating one of a special class identifier and a concrete class identifier, wherein the class portion is populated by designating the special class identifier or the concrete class identifier from an offered list, the user interface further including an offer section which displays the offered list.