> For the complete documentation index, see [llms.txt](https://docs.enercalc.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.enercalc.com/e3d-user-manual/interface/toc175916526/toc161393735/toc161393737.md). # Open How to open one or multiple existing ENERCALC 3D model files for shared data and result comparison. File > Open opens an existing ENERCALC 3D model file. You may open one or multiple files at one time. To open multiple files, simply go to the file list in Open dialog and click the files while pressing CTRL or SHIFT. ![](https://560001759-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FWNe8U6EBBBdUJHdb2X9G%2Fuploads%2Fgit-blob-6c7c08c9b5148c871ae556a16ad69f6f18092889%2FFASTFR~1_img4.png?alt=media) Multiple Document Interface (MDI) makes it easy for you to share data and compare results between different models. Multiple windows or views may be associated with a single file. These windows may have different display settings with respect to zooming, panning, displaying or hiding various structural entities, annotations, etc. For example, you may have one window for geometry, another window for loading diagrams, and yet another window for moment and shear diagrams. --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter: ``` GET https://docs.enercalc.com/e3d-user-manual/interface/toc175916526/toc161393735/toc161393737.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.