{"action":"created","issue":{"url":"https://api.github.com/repos/tbeu/Modelica/issues/1134","repository_url":"https://api.github.com/repos/tbeu/Modelica","labels_url":"https://api.github.com/repos/tbeu/Modelica/issues/1134/labels{/name}","comments_url":"https://api.github.com/repos/tbeu/Modelica/issues/1134/comments","events_url":"https://api.github.com/repos/tbeu/Modelica/issues/1134/events","html_url":"https://github.com/tbeu/Modelica/issues/1134","id":197089046,"number":1134,"title":"correct usage of units in MSL?","user":{"login":"modelica-trac-importer","id":22202507,"avatar_url":"https://avatars.githubusercontent.com/u/22202507?v=3","gravatar_id":"","url":"https://api.github.com/users/modelica-trac-importer","html_url":"https://github.com/modelica-trac-importer","followers_url":"https://api.github.com/users/modelica-trac-importer/followers","following_url":"https://api.github.com/users/modelica-trac-importer/following{/other_user}","gists_url":"https://api.github.com/users/modelica-trac-importer/gists{/gist_id}","starred_url":"https://api.github.com/users/modelica-trac-importer/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/modelica-trac-importer/subscriptions","organizations_url":"https://api.github.com/users/modelica-trac-importer/orgs","repos_url":"https://api.github.com/users/modelica-trac-importer/repos","events_url":"https://api.github.com/users/modelica-trac-importer/events{/privacy}","received_events_url":"https://api.github.com/users/modelica-trac-importer/received_events","type":"User","site_admin":false},"labels":[{"id":504702134,"url":"https://api.github.com/repos/tbeu/Modelica/labels/discussion","name":"discussion","color":"cccccc","default":false}],"state":"open","locked":false,"assignee":{"login":"beutlich","id":14896695,"avatar_url":"https://avatars.githubusercontent.com/u/14896695?v=3","gravatar_id":"","url":"https://api.github.com/users/beutlich","html_url":"https://github.com/beutlich","followers_url":"https://api.github.com/users/beutlich/followers","following_url":"https://api.github.com/users/beutlich/following{/other_user}","gists_url":"https://api.github.com/users/beutlich/gists{/gist_id}","starred_url":"https://api.github.com/users/beutlich/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/beutlich/subscriptions","organizations_url":"https://api.github.com/users/beutlich/orgs","repos_url":"https://api.github.com/users/beutlich/repos","events_url":"https://api.github.com/users/beutlich/events{/privacy}","received_events_url":"https://api.github.com/users/beutlich/received_events","type":"User","site_admin":false},"assignees":[{"login":"beutlich","id":14896695,"avatar_url":"https://avatars.githubusercontent.com/u/14896695?v=3","gravatar_id":"","url":"https://api.github.com/users/beutlich","html_url":"https://github.com/beutlich","followers_url":"https://api.github.com/users/beutlich/followers","following_url":"https://api.github.com/users/beutlich/following{/other_user}","gists_url":"https://api.github.com/users/beutlich/gists{/gist_id}","starred_url":"https://api.github.com/users/beutlich/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/beutlich/subscriptions","organizations_url":"https://api.github.com/users/beutlich/orgs","repos_url":"https://api.github.com/users/beutlich/repos","events_url":"https://api.github.com/users/beutlich/events{/privacy}","received_events_url":"https://api.github.com/users/beutlich/received_events","type":"User","site_admin":false}],"milestone":null,"comments":14,"created_at":"2016-12-22T03:50:44Z","updated_at":"2016-12-22T03:53:05Z","closed_at":null,"body":"**Reported by dzimmer on 27 May 2013 15:18 UTC**\nThe correct usage of units within the MSL shall be checked. Many tools (as Dymola for instance) apply only very relaxed checks for units because otherwise (according to their reports) too many examples in the MSL would break.\n\nEspecially, one issue is annoying: Reals of units 1 are treated the same way as Reals with an undefined unit. Hence you can write stuff like this:\n\n```mo\nmodel Foo\n  Modelica.SIunits.RelativeDensity x;\n  parameter Modelica.SIunits.Voltage y;\nequation \n  x = y;\nend Foo;\n```\n \nwithout getting a warning in some tools. We suggest that the MSL is corrected that Reals of unit 1 have to comply with unit checks whereas Reals with undefined unit do not have to comply with unit checks. So the following code shall not generate a warning:\n\n```mo\nmodel Foo\n  Real x; //no unit specified means \"\" according to the spec.\n  parameter Modelica.SIunits.Voltage y;\nequation \n  x = y;\nend Foo;\n```\n\nThis is currently (rightfully) the case in most unit checkers.\n\nWe know it is difficult to comply to unit checks since they are not standardized (it is not part of the specification) but when tool developers complain that they cannot improve their checks because otherwise they break standard library code the dog really starts to eat its own tail.\n\nThis topic probably requires discussion between the library group and the design group and vendors. Maybe this issue also has been addressed for the new MSL version but we are not aware of it.\n\n\n----\n\nMigrated-From: https://trac.modelica.org/Modelica/ticket/1134"},"comment":{"url":"https://api.github.com/repos/tbeu/Modelica/issues/comments/268712405","html_url":"https://github.com/tbeu/Modelica/issues/1134#issuecomment-268712405","issue_url":"https://api.github.com/repos/tbeu/Modelica/issues/1134","id":268712405,"user":{"login":"modelica-trac-importer","id":22202507,"avatar_url":"https://avatars.githubusercontent.com/u/22202507?v=3","gravatar_id":"","url":"https://api.github.com/users/modelica-trac-importer","html_url":"https://github.com/modelica-trac-importer","followers_url":"https://api.github.com/users/modelica-trac-importer/followers","following_url":"https://api.github.com/users/modelica-trac-importer/following{/other_user}","gists_url":"https://api.github.com/users/modelica-trac-importer/gists{/gist_id}","starred_url":"https://api.github.com/users/modelica-trac-importer/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/modelica-trac-importer/subscriptions","organizations_url":"https://api.github.com/users/modelica-trac-importer/orgs","repos_url":"https://api.github.com/users/modelica-trac-importer/repos","events_url":"https://api.github.com/users/modelica-trac-importer/events{/privacy}","received_events_url":"https://api.github.com/users/modelica-trac-importer/received_events","type":"User","site_admin":false},"created_at":"2016-12-22T03:53:05Z","updated_at":"2016-12-22T03:53:05Z","body":"**Comment by otter on 21 Jun 2014 17:54 UTC**\nIt seems in MSL 3.2.1 all units are correct"}}
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