In the perfect world, your boss will hand you a CD-Rom with the completed architectural, civil, structural, landscape and mechanical drawing sets. All 600 sheets in this volume will have been drawn in AutoCAD R13c4 or R14. All of the layers, linetypes and x-refs are well documented in the read.me files that each firm has provided.......NOT! In the real world of designs, there is not even enough time to just produce drawings let alone burn CD-Roms and write documentation to accompany drawings. This leads us to Julys' commands of the month, List and DDmodify. For the rest of us who are in a production environment, these two commands are used regularly when dealing with drawings that are produced by others or even drawings that are created internally, that you are not familiar with.

LIST
When the time comes that you need to work with a drawing that you did not generate, it is not always obvious as to what type of entities the drawing contains or even which layer or line type they are drawn on. For instance, you may not be able to tell if a line on screen is a simple line, a polyline, or the edge of a polygon. The List command, located in the inquiry portion of the edit pulldown, sole purpose is to identify drawing entities and listing there properties. Once invoked, the List command allows you to select entities using the standard AutoCAD entity selection techniques. Be forewarned; the list command, even for a single entity, may generate reams of output, for instance, here are a few different entities, some look complex and others not so complex. When the List command is invoked and the 3D block is selected the List command reveals that these entities are really just one entity. The entity is a 3D solid that resides on a layer called block, the virtual space the entity was created in is shown and X, Y and Z coordinates are all given as well as its handle identifier. Next the arc is selected. At the first text screen, List shows us that the arc is a polyline, which just by looking at it, is impossible to tell; and gives its layer name and several vertices. What may be considered as important on this text screen is the arcs focal point which is the X and Y values given as the arcs' center. Other important information is shown in the coordinates given as the start and end points and the arcs' radius. The second text screen shows the arcs' area and its length. There is one very important thing that needs to be said here, that is, the output from the list command does not describe the entities color, linetype or thickness. List will show these properties if the color and linetype are not set to BYLAYER and the thickness is not set to zero. The list command's output will change based on the type of entity that it is reporting on. For text, it will show information on the texts' height, style and the value (text); for viewport entities, List will report whether the viewport is active or inactive. Because the List command's output is highly detailed, it may offer more information than is required. If all you want to know is a layer or the thickness of an entity, you may want to use the DDmodify command.

DDmodify
The DDmodify command's primary purpose is to modify entities, however, it is an excellent command to discover valuable entity information. To start the command, type at the command prompt, DDmodify or select the Entity option from the Modify pulldown. The DDmodify will only select one entity at a time, this is because DDmodify is not a report like List but is a entity editor. When an object is selected, in this case a 3D sphere, a dialogue box will appear that gives information regarding that object. Notice that the sphere has 37+ vertices, if you were using the List command, this vertex would have been several pages down in the text window. The dialogue box that DDmodify shows, like the List command, is dependant on the type of entity that is selected. If the word PAUG is selected, the DDmodify not only shows the properties of the text and, if you need, you could edit the text or change any of its properties. The DDmodify command quickly and in a more user friendly way, shows you about the same information as the List command but any entity that is selected with DDmodify, is editable.