Function Syntax: DelUnusedBlocks N/A short_description: 🚀 DelUnusedBlocks is an AutoCAD AutoLISP and DCL cleanup utility for detecting and deleting unused block definitions from the active DWG drawing. 🧹 It scans the block table, removes inserted blocks from the candidate list, excludes xrefs, layout blocks, anonymous blocks, and dependent records, then shows only deletable unused block names. ✅ The main benefit is faster AutoCAD drawing cleanup, reduced DWG clutter, better block library management, and improved CAD standards control. command: 🧰 Load the LISP with APPLOAD or an AutoCAD startup loading method. 🚀 Run DelUnusedBlocks to open the generated DCL dialog named Delete Unused Blocks. 📄 Main source file: DelUnusedBlocks_DCL.lsp. 💾 Settings are saved in DelUnusedBlocks.cfg using ROAMABLEROOTPREFIX, DWGPREFIX, TEMPPREFIX, or the current folder as fallback locations. description: 📘 This AutoCAD cleanup tool helps the user delete unused block definitions through a DCL multi-select dialog instead of manual block table inspection. 🔍 The program uses tblnext on the BLOCK table and checks DXF group code 70 to exclude non-deletable records. 🧠 It removes block names that still have inserted references by using ssget "_X" with an INSERT filter. 📋 The dialog lists unused block definitions, supports multi-selection, Select All, Select None, and an optional confirmation toggle. 🧹 Selected unused definitions are deleted with ActiveX database calls such as vla-item and vla-delete. Important: this is a cleanup command that deletes selected unused block definitions from the DWG block table. helper_function: 🚀 Command entry point - c:DelUnusedBlocks starts the scan, DCL dialog, settings read, user selection, and deletion workflow. 🔍 Unused block detection - DUB:block-inserted-p checks whether a block name still has INSERT references in the drawing. 🔒 Protected block filtering - DXF 70 flag mask skips anonymous blocks, xrefs, externally dependent blocks, xref-dependent definitions, resolved xrefs, and layout blocks. 📋 DCL generator - DUB:write-dcl and DUB:dcl-text write a temporary DCL file with a multi-select list, selection buttons, confirmation toggle, Delete, and Cancel. 🧠 Index and name mapping - DUB:names->index-string and DUB:index-string->names converts saved block names to DCL list indexes and back. 🧹 Deletion engine - DUB:delete-selected and DUB:delete-block delete selected unused block definitions using AutoCAD ActiveX methods. ⚠️ Confirmation prompt - DUB:yes-p asks Yes or No before deletion when confirmation is enabled. 💾 Persistent settings - DUB:read-cfg and DUB:write-state save confirmation, last selected names, and dialog coordinates in DelUnusedBlocks.cfg. 🔐 Safe COM wrapper - LM:catchapply uses vl-catch-all-apply to reduce hard failures when COM operations fail. functionalities: 🚀 Dedicated AutoCAD cleanup command - runs DelUnusedBlocks for unused block definition cleanup. 🔍 Automatic unused block scan - finds block definitions that are not inserted in the active DWG. 🔒 Protected record exclusion - skips xrefs, dependent blocks, layout records, and anonymous/system definitions. 📋 Generated DCL interface - shows unused blocks in a multi-select dialog. 🟢 Select All - marks every detected unused block definition. ⚪ Select None - clears the DCL selection for manual picking. ⚠️ Confirmation option - can ask the user before deleting selected block definitions. 🧹 Delete selected unused blocks - removes chosen unused definitions from the block table. 💾 Save user settings - remembers dialog position, confirmation state, and previous selections. 📊 Command-line report - prints deleted names and the total number of deleted unused blocks. 🔐 Clean cancel behavior - preserves settings and exits without deleting when cancelled. result: ✅ The final result is a cleaner AutoCAD DWG with selected unused block definitions removed from the drawing database. 🚀 The tool improves block cleanup speed, CAD standard maintenance, drawing audit preparation, DWG performance hygiene, and project handover quality. additional_info: 🔴 Destructive action: selected unused block definitions are deleted, so save or back up important drawings before running cleanup. 🔒 Inserted blocks are protected because the routine excludes block definitions that still have matching INSERT references. ⚠️ The code does not create a custom undo mark. AutoCAD standard undo behavior may still apply depending on command history. 📌 In complex dynamic block or anonymous block workflows, review the detected list carefully before deleting. 🧰 Requires AutoCAD Visual LISP and COM support through vl-load-com.