On Tue, 19 Nov 2019 at 11:10, James Cameron wrote: > Path of least resistance was often to grab the headings from a > previous requirements document and then fill in the gaps. > > A useful approach. And of course, one which sometimes leads to extremely humorous and sometimes just plain wrong documents. In a past lifetime in corporate employ I saw various documents (not PCB related) that had been prepared using large amounts of copy & paste and in which occasional or sometimes very large amounts of material were not only obviously 'just pasted in' but sometimes very or totally inapplicable. While copy and paste and templates are very useful they require substantial extra vigilance to overcome the tendency to skim through material which the brain is happy to accept as is. Where material is reused there is a strong need to read each sentence "for meaning" and to fight the strong(er) tendency to see things which are not there and to un-see things which are not. ______ Related aside: At one stage I spent signifiant effort on probing component data sheets (mainly Asian and mainly LED related) to see if it could be established whether they had any prospect of being reasonably well related to the actual product or even in any meaningful way at all genuine. A useful approach which I have used often since is to find a phrase in the text which seems liable to be unique - or which should be if the document is a genuine reflection of measurements on a specific product. This (too) often turned up LED datasheets from the same manufacturer which contradicted each other, data sheets from other Asian manufacturers which were obviously either the ancestors or descendants on nth cousins of the one in hand, or, interestingly, data sheets from reputable name brand manufacturers with the same text - but, usually when this happened, data which was clearly spurious or just plain wrong. Such discoveries are generally an indication that one should sidle away slowly, no sudden moves, hands in sight. I had a local copy on disk of the NASA PCB document that I cited in another message (https://nepp.nasa.gov/index.cfm/27505). I did not have an immediate link to the original so web searched on This webpage is intended to be used as an introduction to printed circuit board (PCB) product assurance information for uses by NASA projects Returning https://www.google.com/search?q=3DThis+webpage+is+intended+to+be+used+as+an= +introduction+to+printed+circuit+board+(PCB)+product+assurance+information+= for+uses+by+NASA+projects&rlz=3D1C1CHBF_enNZ834NZ839&oq=3DThis+webpage+is+i= ntended+to+be+used+as+an+introduction+to+printed+circuit+board+(PCB)+produc= t+assurance+information+for+uses+by+NASA+projects&aqs=3Dchrome..69i57.1730j= 0j4&sourceid=3Dchrome&ie=3DUTF-8 This returned a significant number of dead or spurious or highly dangerous links (SD card contents available for download - click here ...), either allegedly containing the text or in some cases actually doing so, and several gems. eg "Risk-based safety and mission assurance: Approach and experiences in practice " NASA 2018 17 pages "Space product assurance - Qualification and procurement of printed circuit boards " March 2019 ESA 270 pages .... Links in another post. Russell --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .