François, The discussion about this has also been brought to the forum, here: https://forum.openstreetmap.org/viewtopic.php?id=64825
I'm unsure if it is better to continue it here in the ML, there in the forum, or in both places... On 2018-12-20 01:04, François Lacombe wrote: > > Le mer. 19 déc. 2018 à 22:26, Richard <ricoz....@gmail.com > <mailto:ricoz....@gmail.com>> a écrit : > > the OSM tag chain should be imho used only for very common things because > each member > of the chain will turn up as a "top level" tag in the database and > taginfo. > > > We are using such chains in Power, Pipeline and Telecom groups. It works well > : > power=transformer + transformer=distribution + voltage:primary=20000 + > voltage:secondary=400 > man_made=street_cabinet + street_cabinet=telecom + telecom=exchange + > telecom:medium=copper + operator=Orange "Transformers" is a perfect example of "namespacing done backward". Why "voltage:secondary=220"? In a correctly namespaced world it would be "secondary:voltage=220". I understand that in spoken English you can say "the **voltage** of the *secondary *is *220 *Volt", and that's probably why those keys have been built with the terms in that particular order. (/BTW, logic and wording is very different in different cultures and languages. I think it wouldn't had been in that order in, say, German: can a german speaker please confirm that?/) Transformers can have and very often have more than one secondary: you have dealt with that using things like "voltage:tertiary=*" and the likes (windings:tertiary=*, I suppose...). And what if the transformer has 3 secondaries? Or 4? Isn't "secondary:1:voltage=200" better? Don't you see that's more logical and expandable? Don't you see that here we assign a quantity (220) to something that has the correct dimensions (voltage), like in the previously globally defined key "voltage=*"? Don't you see how with that syntax everything related to the first (/second, third, fourth,... nth/) secondary (/wingdings, current, whatever.../) would be grouped under "secondary:n:*="? And if transformers weren't meant to be a "/namespaced thing/", why using the columns? Why not voltage_secondary=* ? Don't you see that with the transformers a *new first level keyword*, "rating=*" have been implicitly defined and documented in the transformers page and how that keyword can be useful in other contexts... or namespaces, if you prefer? BTW, what is that telecom:medium=copper thing (https://wiki.openstreetmap.org/wiki/Key:telecom:medium)? /"Telecoms" /do not have a medium: local loops have. Is that meant to be a namespaced thing? Have this being debated/approved? I have seen it applied to buildings: what is the meaning of that? > Adding power: and telecom: prefixes would be seriously bad to encourage for > contribution and extremely redundant. To the contrary! Please read in the forum my rationale explaining exactly how that would be beneficial... > > Furthermore, refining of well used tags often get discouraged because of > their usage. > This dosn't include the redundancy in namespaces' prefixes which is worse. > > > If used extensively for attributes I would consider it polution of the > database. > It is also much less flexible as you can specify only one attribute at a > time. > > If you have to define more than one attribute with the same name it may be > the attribute isn't weel defined. > > Have you examples please? > > All the best > > François Sorry, I'm really now on the verge (/less than 24 hours.../) of a small journey, so I would probably be unable to answer/contribute anymore until January, 6. Cheers, Sergio
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