Revision blocks

Blueprint Compositions, Continued Revision blocks Revision blocks are only needed on drawings if changes or improvements are made to the original part or assembly. The addition of a letter to the original number and a brief description of the revision in the revision block show that a drawing is revised. Subsequent revisions replace the previous letter with the next letter of the alphabet. Locate revision blocks above the title block on drawings larger than “A” size. On “A”-sized drawings, locate the revision block in the upper-right corner. Figure 1-40 illustrates how revision blocks on drawings append to the title block. Figure 1-40.—Revision block appended to a title block. Application blocks Application blocks identify directly or by reference the larger unit that contains the part or assembly on the drawing. The next assembly (NEXT- ASS’Y) column contains the drawing number or model of the next larger assembly. The used on column shows the model number or equivalent designations of the assembled units part. Locate application blocks appended to the far left side of title blocks. Continued on next page 1-52