# "Block Definition"Dialog Box [GstarCAD 2018](Help%20System/GSTARCAD/2018/Index.md) → [Commands](Help%20System/GSTARCAD/2018/Commands/(Commands).md) → [03 Dialog Boxes](Help%20System/GSTARCAD/2018/Commands/03%20Dialog%20Boxes/(Dialog%20Boxes).md) This dialog box is used to define and name a block.  Relative glossary: **Name:**Specify the name of block. The name could contain 255 characters at most, including letters, numbers, spaces, and any other special characters which are not used by Operation System or Gstarcad programs. The block name and definition are saved in current drawing. **Preview:**Selecting the name of existing block under the name option, it will display the preview of existing block. **Base Point:**Specify a base point for block insertion. The default value is 0,0,0. > **Specify On-screen:** > When closing the "Block Definition" dialog box, it prompts to specify insertion base point. > **Pick point:** > Temporarily close the dialog box for users picking insertion point. **X:** Specify the X coordinate of insertion point. > **Y:** Specify the Y coordinate of insertion point. **Z:** Specify the Z coordinate of insertion point. **Objects:**Specify objects to be contained in block and determine how to deal with all of those objects, to retain or delete or convert to block. > **Specify On-screen:** > Close the dialog box and prompt to select object. > **Select object:**Temporarily close the dialog box and allow users to select objects. After selecting all objects, press ENTER to return back to this dialog box. > **Quick select:**Display the Quick Select dialog box. Users could use this dialog box to define selection set. > >  > **Retain:** > After creating a block, the selected objects will be retained in the drawing for easy distinguishing. > **Convert to Block:**After creating a block, convert all selected objects to be a block instance in drawing. > **Delete:** After creating a block, delete all selected objects. **Behavior:**Specify the behavior of selected block. > **Annotative:** Specify the block to be annotative. > **Match block orientation to layout:**Specify the block orientation in paper space match the orientation of layout. If the Annotative option has not selected, this option will not be available. > **Scale Uniformly:** Specify whether to scale the block reference uniformly. > **Allow exploding:** > Specify whether to allow exploding the block reference. **Settings:** Specify block settings. > **Block unit:** > Specify the unit when inserting a block. > **Hyperlink:** Open the "Insert Hyperlink" dialog box from which users could link a hyperlink with the block definition. **Description:**Specify the description of block. **Open in block editor:**After clicking "OK", the current block definition will be opened in block editor. ## Other versions with matching text [GstarCAD 2016](../../../2016/Commands/03%20Dialog%20Boxes/Block%20Definition-Dialog%20Box.md) · [GstarCAD 2017](../../../2017/Commands/03%20Dialog%20Boxes/Block%20Definition-Dialog%20Box.md) · [GstarCAD 2019](Help%20System/GSTARCAD/2019/Commands/03%20Dialog%20Boxes/Block%20Definition-Dialog%20Box.md) · [GstarCAD 2020](Help%20System/GSTARCAD/2020/Commands/03%20Dialog%20Boxes/Block%20Definition-Dialog%20Box.md) · [GstarCAD 2021](Help%20System/GSTARCAD/2021/Commands/03%20Dialog%20Boxes/Block%20Definition-Dialog%20Box.md)