NFPA 1999-2018 Standard on Protective Clothing and Ensembles for Emergency Medical Operations.
3.2.5 Shall. Indicates a mandatory requirement. 3.2.6 Should. Indicates a recommendation or that which is advised but not required. 3.2.7 Standard. An NFPA Standard, the main text of which contains only mandatory provisions using the word “shall” to indicate requirements and that is in a form generally suitable for mandatory reference by another standard or code or for adoption into law. Nonmandatory provisions are not to be considered a part of the requirements of a standard and shall be located in an appendix, annex, footnote, informational note, or other means as permitted in the NFPA Manuals of Style. When used in a generic sense, such as in the phrase “standards development process” or “standards development activities,” the term “standards” includes all NFPA Standards, including Codes, Standards, Recommended Practices, and Guides.
3.3* General Definitions. 3.3.1 Accessories. An item, or items, that are attached to the certified product that are not necessary to meet the require- ments of the standard. 3.3.2 Aferflame. Persistent flaming of a material after the ignition source has been removed. 3.3.3 Afterlame Time. The length of time for which a mate- rial continues to flame after the ignition source has been removed. 3.3.4 Arch. The bottom curve of the foot from the heel to the ball. 3.3.5 Barrier Layer. The layer of garment material, glove material, footwear material, or face protection device material designated as providing body fluid-borme pathogen resistance. 3.3.6 Biological Terrorism Agents. Liquid or particulate agents that can consist of biologically derived toxin or patho- gen to infict lethal or incapacitating casualties. 3.3.7 Body Fluid-Bormne Pathogen. An infectious bacterium or virus caried in human, animal, or clinical body fluids organs, or tissue. 3.3.8 Body Fluids. Fluids that are produced by the body, including，but not limited to, blood, semen, mucus, feces, urine, vaginal secretions, breast milk, amniotic fluid, cerebro- spinal fluid, synovial fluid, sweat, vomit, and pericardial fluid.NFPA 1999 pdf download.