In addition to spaces and on the title block, which are provided for approval signatures, a second SATISFACTORY TO block may be required when an outside activity requests a drawing. The extra SATISFACTORY TO block is identical to the SATISFACTORY TO space in the title block but is located adjacent to title block space .

A REVISION block contains a list of all revisions made to the drawing. On construction drawings, the revision block is placed in the upper right-hand corner. Basically, all revision blocks provide the same information; only the

Figure 3-22.-Format used in preparing revision blocks.

sizes of the blocks differ (fig. 3-22). Revision information is entered chronologically starting at the top of the revision block.

Revision letters are used to identify a change or revision to a drawing. Uppercase letters are used in alphabetical sequence, omitting the letters I, O, Q, S, X, and Z. The first revision to a drawing is assigned the A. On a drawing, all changes that are incorporated at one time are identified by the same revision letter. The changes may be numbered sequentially to permit ready identification of a specific change. In this case, the appropriate serial number will appear as a suffix to the revision letter (for example, A1, A2, A3, etc.). Whenever possible the revision letter will be placed near the actual change on the drawing. It should be placed so it is not confused with other symbols on the drawing. Usually, the revision letter is placed inside of a circle or triangle If a circle or tri-angle is used on the drawing, it should also be used in the revision block.

A brief description of each change is made in the description column, adjacent to its revision letter, in the revision block. The approval signature and date of revision are also entered in the appropriate columns. For all drawings prepared by Architect/Engineer (A/E) firms, the revision block should include a separate PREPARED BY column (fig. 3-22, view B).

The zone column on the standard revision block is normally omitted on construction drawings but may be used in reviewing maps. Zones are indicated by alphabetical or numerical entries and are evenly spaced in the margin for locating an object on the drawing or map. Use of zoning is described in DoD-STD-100C. Like title blocks, revision blocks may vary with each command, and you will be required to follow command guidelines. The procedure for making revisions to drawings is covered in DoD-STD-100C.