MAINTAINABILITY DESIGN TECHNIQUES METRIC - AcqNotes.com

Downloaded from http://www.everyspec.com on 2011-10-29T14:56:01.DOD-HDBK-791(AM)2. Label each control and display.3. Indicate the functional result of the controlmovement—e.g., increase, decrease, slower. Where applicable,the label may include calibration data. Labelsshould be visible during operation (see par. 6-5.2). Thefunctional result term should be at the end of an arrow.4. Label instruments in terms of what is being measuredor controlled; the use and purpose should also beconsidered.5. Indicate functional relationships when controlsand displays must be used together, e.g., adjustmenttasks.6. Avoid highly similar names for different controlsand displays.Once the purpose or intent of the label has been determined,the following guidelines are applicable for displayingthe information:1. Make label content brief but explanatory– use asfew words as possible to convey the intended meaning.Special markings or symbols, e.g., arrows and pictorials,should be considered only when they will unambiguouslyconvey meaning in a more direct manner than severalwords. Labels should only provide reminders, as shown inFig. 6-5, for the trained technician; they need not providecomplete instructions.2. Use abbreviations only when they will be meaningfulin the overall statement. When used, standardabbreviations should be selected in accordance with MIL-STD-12 (Ref. 14), MIL-STD-411 (Ref. 15), MIL-STD-783 (Ref. 16). If these references specify the same abbreviationfor more than one function, such abbreviationshould not be used for more than one function. If a newabbreviation is required, its meaning should be obvious tothe intended observer (Ref. 4).3. Itemize—when a label lists a number of steps to beperformed in an established sequence—each step, ratherthan compose the steps, in narrative form as illustrated byFig. 6-6.Figure 6-5. Example of Label Brevity (Ref.11)Figure 6-6. Example of Step-by-StepInstructions4. Make part identification and equipment labelsconsistent with both the technical manuals and supplycatalogs.5. Compose labels so that they read from left to rightas indicated in Fig. 6-7. Vertical arrangements should beused only when they are not critical for personnel safetyand task performance and where space is limited. Whenused, vertical labels should read from top to bottom (Ref.4).6. Specify directional arrows that are as clearly recognizableand identifiable as possible when read at adistance. The direction of arrows with sharp angles andclean lines, as illustrated in Fig. 6-8 (Ref. 9), is less easilymisinterpreted at a distance than that of arrows withwider angles and broader overall width-to-angle ratios.The following Military Standards and Military Specificationsshould be referred to to insure that the format ofthe label content is consistent with the military requirements:1. MIL-STD-130 (Ref. 3)2. MIL-STD-195 (Ref. 17)3. MIL-STD-411 (Ref. 15)6-8