Reference Files

A reference file is a type of overlay. Information in one drawing can be overlaid on a different drawing, eliminating the need to redraw information. Proper use of reference files will result in significant time savings and greater coordination of drawings.

Reference files are most commonly used as background information. Generally, a project will have a master site plan depicting the existing site features and topography.  This master site plan is then used as a reference file, whenever existing site information is needed.

Another typical use for a reference file is the outline of a structure. The structural floor plan may be used as a reference file on the Mechanical and Electrical floor plans. This results is all plan drawings having identical backgrounds. Any revisions to the building are made in the Structural drawing only, and are immediately reflected in the other plans. Conflicts and interferences become readily apparent.

Reference Files are part of the Project

A file used as a reference file is a part of the project. Drawings from other projects should never be used as permanent reference file attachments. Generally, the only files used as reference files are other drawings in the same project, and one or two master files. The master files are not actual drawings, but usually provide background information such as topography or existing structures.

Deciding Which Reference Files to Use

It is very important to select reference files carefully and logically. Although it is possible to attach many reference files, working with more than 4 or 5 reference files becomes confusing and difficult.

When selecting files to use as reference files, follow these basic principals. 

Reference files can also be temporarily attached to a design file to aid in creating a drawing. For example, when drawing exterior building elevations, attach the building sections and framing as reference files to coordinate and verify all dimensions.

Before creating a new drawing, research any existing drawings to see if coordination is required. If a file already exists, such as the sections or framing elevations in the example above, attach those files as a temporary reference file. All new work should be drawn on top of the existing work in the reference files.  By superimposing related graphics on top of each other, the final product will be more accurate and any conflicts will be noticed more easily.  Temporary reference files should always be detached before the drawing is exited.

Reference File Names

Reference Files are either project drawings or a master file. All reference files are named either with a project drawing file name, or with a structure number and descriptor.

Examples:

  1. The structural floor plan drawing is used as a reference file for the background to the mechanical drawing. The structural floor plan file name is  "123S003.R00". This same file becomes the reference file to the mechanical drawing, and retains the same name.

  2. The existing site topography covers a large area, and is used as the background for several drawings that make up the site plans. Since the existing site topography is not a project drawing, it does not have a project drawing number. However, it should still have the structure number identification (first 1 to 4 characters of file name). In this example, the reference file would be named  "123XSITE.MST".

The section on File Names describes the composition of file names and file name extensions. All file names shall fall within the parameters set by that section of the manual.

Reference File Logical Names

Each reference file attachment should be given a logical name. The logical name should be an abbreviation of the full file name.  For example, when attaching the file  104E301.R00 as a reference file, the best logical name to use is  E301.  If the drawing is attached to the file twice, then the logical names would be E301A and E301B.

Logical Names control the way the reference file is plotted. Specific prefixes are used to aid in plotting.  The prefixes "SC" and "X" are used to obtain specific screening effects when plotting. See the section on plotting for a complete description of reference file logical names and their effects on plotting. All CAD files produced for the District should follow this logical name convention, regardless of the software used for plotting.

Named Views and Reference Files

Reference files should never be attached using the saved/named view method. If a saved view is used to attach a reference file, it is impossible to reattach it in exactly the same location. Drawings with reference files attached by named view will not be accepted.

Reference File Levels

When a reference file is attached to a file, all levels should be turned OFF, except for the specific levels that are required.  Any levels that are blank should be turned OFF.  This will eliminate the problem of elements unintentionally "appearing" on a drawing when the reference file is modified.

Reference File Attachments

When using reference files, try to avoid moving, scaling, or rotating the reference file. If it is necessary to move and/or scale the file, try to simplify the process by selecting an even number of feet for the move, or an obvious rotation or scale point.

If a reference file is attached to several different project drawings, and is rotated and/or scaled in each of those drawings, then the scale point and rotation point should be consistent throughout each drawings and throughout the entire project.

For all drawings that reflect an XY or NE coordinate system, such as civil drawings and survey drawings, reference files should NEVER be rotated. If rotation is necessary, the VIEW should be rotated rather than the file. This will ensure that the coordinate information will remain accurate and "true". The rotated view angle should be documented in the reference file documentation.

Use Level 131 for Reference File Documentation

Some reference file attachments are very complex and the description provided by the reference file documentation cell, REFDOC, is not adequate to fully describe the attachment. In these cases, level G-SPCL-REFR-NPLT (level #131) may be used to show additional information about the reference file attachment.

Level G-SPCL-REFR-NPLT may be used to show the clipping boundary of the reference file, the rotation or scale point of the reference file, or any other information that will help in reconstructing the attachment.

Save Settings With Reference Files

Always leave a CAD file with the correct reference files displayed. A file should never be "saved" with the reference file display turned off, with temporary reference files attached or with extra levels turned on.  The intent is to leave a file so that the next user can work on it without having to do any set up.

Reference File Documentation

Each reference file attachment shall be documented in the design file where it is attached. If a specific file is attached more than once, it should be documented for each attachment. Place the cell, REFDOC, from the Common Cell Library, at the right side of the drawing border at the same scale as the plot scale, in every file where a reference file is used. This provides a form where all information about the reference files can be entered. The form contains data fields for entering all information.

The documentation form includes the following information for each reference file attachment.

Any information required to reconstruct the reference file attachment should be included in the documentation.  The user should assume that someone who is completely unfamiliar with the project will have to reconstruct the drawing, and the documentation should make that process as easy as possible.

Hard Copy of Reference File Documentation

A hard copy plot of each reference file documentation sheet shall be submitted with the final submittal of the CAD files.