Dear List, {This is a cross post - please reply to the tagging mailing list or the proposals [2] talk page. Please forward to local mailing lists as appropriate }
- - - Announcement - - - Several attempts have in the past been made to develop a tagging scheme that is capable of handling the more complex access restrictions (e.g. No motor vehicles between 10am and 6pm except vehicles less than 5 meters [1]). Voting has started on the latest proposal [2]. Due to the wide reach of this proposal, I am announcing it here and encouraging users to carefully consider the proposal and vote. To help, I have summarised the alternate proposals (in alphabetic order and including this one) [3]. Note that not all of these are in active development. I have also attempted to write the case for and case against this proposal. As a reminder of terminology, a Tag consists of 'Key' and a 'Value' pair (key=value). For example "maxspeed=80". - - - Case "For" - - - Extract by the proposal author from the proposal's wiki page [2]: //start quote// This proposal overcomes some objections to previous attempts at tagging conditional restrictions. * No variable parts in the key. This is essential as keys are used to search for data in the OSM database. If a key comprises a variable part it can no longer be retrieved during search unless you know the exact condition you are looking for (database searches do not allow wildcards in search keys). Variable parts in keys will also lead to an undesired proliferation of unique keys. * Avoids the requirement for problematic characters in the key such as "<" or ">" * Clear distinction between scope (transportation mode, vehicle class) and condition. * Possibility to combine conditions using operators. * The conditional restriction can be defined as a single tag. Some prior proposals required multiple tags such as hour_on and hour_off tags. For objects having multiple restrictions this could lead to problems (which tags belong to which restriction?) * The syntax of the key is essentially identical to the established access key syntax with an additional qualifier ":conditional". * Backward compatible. Doesn't break any established tagging schemes. //end quote// - - - Case "Against" - - - Extracts from those who have currently (18/09/2012) voted against the proposal: //start quotes// * Breaks a lot of tags which came "natural" to the mappers, e.g. maxspeed:wet=80 becomes maxspeed:conditional=80 @ wet, access:disabled=yes becomes access:conditional=yes @ disabled, … * Creates arbitrary distinctions: depending on whether something is defined to be a transportation mode or a condition, it belongs either in the key or in the value, e.g. "hgv" is a transportation mode, but "hazmat" is a condition * Has bad editor support: adding a conditional restriction like "speed limited to 80 when wet" to a set of ways is quite complicated if there are already different restrictions on those ways; merging :conditional tags in JOSM by default produces a value that is completely wrong, yet cannot be identified as wrong. * It's to difficult for users, not intuitive. There are too many subkeys and subvalues. I think value with logic instruction (AND) (and maybe special/new signs (@)) are not good tagging rules. //end quotes// - - - How to Vote - - - 0. Take a moment to conside the pros/cons and their relative importance / how would you do it differently? 1. Log-in to OSM wiki (as far as I know this is not your usual OSM username/password. 2. Navigate to the proposal page [2] 3. Click edit (to the right of the "Voting" heading 4. Add "{{vote|yes}} --~~~~" or "{{vote|no}} --~~~~" after the existing votes. Kind Regards, RobJN [1] Example Signpost: http://wiki.openstreetmap.org/wiki/File:Length_and_time_restriction_2.jpg [2] The Proposal: http://wiki.openstreetmap.org/wiki/Proposed_features/Conditional_restrictions [3] Summary of alternate proposals: http://wiki.openstreetmap.org/wiki/Proposed_features/Advanced_access_tags
_______________________________________________ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk