Function Syntax: LfPredefinedFolders / ExpFltr / ImpFltr Version: 1.1 Date: 20.06.2026 6:38:53PM https://forums.autodesk.com/t5/visual-lisp-autolisp-and-general/lisp-to-export-import-the-layers-properties-filter-in-autocad/td-p/10379159 Description This program allows the user to import a named layer property filter into the current drawing from an external file. It is the companion command to EXPFLTR and reads previously exported .lft files. Purpose The function facilitates the reuse of layer filters across multiple drawings by importing them on demand. Main Functionalities • Prompts the user to select a .lft file containing a previously exported layer filter. • Opens and reads the filter data from the file. • Reconstructs the layer filter definition and adds it to the drawing’s filter collection. • Parses the contents using read-line and vl-read for structured reconstruction. User Prompts • Displays a file selection dialog for the user to choose the import file. • If the user cancels the selection, the routine prints: "\nFile selection canceled." Error Handling • If the file does not exist or is unreadable, the program safely exits without modifying the drawing. Notes • The IMPFLTR command should be used with EXPFLTR exports to maintain consistent data structure. • The routine uses AutoLISP I/O functions like open, read-line, and close. • The imported filter becomes immediately available in the Layer Properties Manager. Description 📥 Import_Layer_Filter is an AutoCAD AutoLISP layer filter transfer tool for exporting and importing property layer filters through .lft, DWG, and DWT sources. 🗂️ It adds predefined project-folder management, multi-filter export and import, and xref-style prefix/suffix handling for NAME== filter patterns. Function Syntax 🚀 Export command: ExpFltr 📥 Import command: ImpFltr 🗂️ Folder manager command: LfPredefinedFolders 📁 Import supports .lft, .dwg, and .dwt sources. SEO Optimized Overview 📥 Import_Layer_Filter is an SEO-friendly AutoCAD layer filter import and export utility for moving property layer filters between drawings, templates, and project folders. 🧱 The routine reads AutoCAD ACAD_LAYERFILTERS and ACLYDICTIONARY data, exports selected filters to .lft files, and reconstructs filters in another drawing. 📦 The enhanced v2 .lft format supports multiple layer filters in one file with a //COUNT header, while the importer still handles older single-filter v1 files. 🗂️ A project folder preset manager stores frequently used Layer_Status paths and allows reordering, saving to file, reloading the LISP, and selecting default import or export locations. 📌 This is useful for CAD managers, Civil 3D project teams, layer-standard migration, xref filter reuse, and template synchronization. Primary Workflow 1️⃣ Load the AutoLISP file in AutoCAD or Civil 3D with APPLOAD or your menu loader. 2️⃣ Run the command shown above from the AutoCAD command line. 3️⃣ Follow the dialog, selection prompts, or file prompts used by Import_Layer_Filter. 4️⃣ Review the command-line report and drawing result before continuing production work. Functionalities ✅ Export multiple AutoCAD layer filters to a single .lft file. ✅ Import multiple filters from v2 .lft files with filter selection. ✅ Import a single filter from v1 .lft files. ✅ Import property layer filters from DWG or DWT source files. ✅ Apply prefix and suffix transformations to layer-name filter patterns. ✅ Manage predefined project folders inside a custom DCL interface. ✅ Save folder configuration back into the LISP-managed preset block. Important Functions and AutoCAD API 🧩 LfPredefinedFolders opens a DCL manager for project folder shortcuts. 🧩 lf:pf-default-dir resolves the active predefined folder into a usable import or export directory. 🧩 _EF_WriteExpDCL builds the multi-filter export dialog dynamically. 🧩 _EF_ApplyPrefixSuffix modifies NAME== patterns for xref and naming-standard workflows. 🧩 getFilterDatas extracts layer filter xrecord data from a source drawing. 🧩 addLayerFilter writes layer filter xrecord data back into the target drawing. 🧩 OpenDrawingDBX reads filters from DWG and DWT files without fully opening them in the editor. Result 🎯 The result is a repeatable layer-filter exchange workflow for AutoCAD and Civil 3D drawings. 🟢 Layer filters can be moved from one drawing or template to another without rebuilding them manually. Operational Notes and Limitations ⚠️ Import skips or reports filters that already exist instead of blindly overwriting them. ⚠️ Source drawings must contain AutoCAD property layer filters for DWG or DWT import to produce results. 🧠 Prefix and suffix logic is powerful but should be checked when used on complex filter expressions. Tags 🏷️ AutoCAD, 🏷️ AutoLISP, 🏷️ Civil 3D, 🏷️ Layer Filters, 🏷️ LFT Import, 🏷️ DWG Standards, 🏷️ Xref Layers, 🏷️ DCL Dialog, 🏷️ CAD Management