revision of SECoP documentation

- created secop_v2017-09-14.rst, based on the GoogleDocs
  SECoP Preliminary V2016-11-30 (rc 2)
- this Document is supposed to contain the full SECoP standard
- created SECoP issues
- moved everything else to "outdated" (kept for reference)

Change-Id: I87d69d1846fc4ed55f1c78b22fd4650d8550152b
Reviewed-on: https://forge.frm2.tum.de/review/16573
Reviewed-by: Enrico Faulhaber <enrico.faulhaber@frm2.tum.de>
Tested-by: JenkinsCodeReview <bjoern_pedersen@frm2.tum.de>

doc/source/protocol/issue_3.rst

@@ -0,0 +1,47 @@
+SECoP Issue 3: SECoP Timestamp Format (closed)
+==============================================
+
+Proposals for the timestamp format are:
+
+ISO time format
+---------------
+
+A date+time string in ISO format like "2017-06-21T13:30:01.123456+02:00"
+
+The fractional seconds are optional, but the timezone has to be given. Z is allowed instead of +00:00.
+
+Advantages:
+
+  * human readable
+
+Disadvantages:
+
+  * needs more conversion efforts, as the time is internally already stored as numbers on mosts systems (supporting math operations).
+  * although the ISO standard is clearly defined, there is a risk that time zones and daylight saving time is not handled properly
+
+Fractional Unix Time
+--------------------
+
+Seconds since 1970-01-01T00:00:00+00:00, represented as a number. When converted to a IEEE double, a resolution of 1 usec can be kept for dates up to 2112.
+
+Advantages:
+
+  * if a double is used as an internal representation, no conversion is needed. using a double as an internal time representation has the advantage, that math operations can be done for free.
+  * relative times for systems with no synchronized clock can be represented easily
+
+Disadvantages:
+
+  * not human readable (or at least not easily: time differences in seconds are still visible)
+
+
+Discussion
+----------
+
+1) Human readibility was judged less important than easy implementaion by the majority.
+
+2) Implementing relative times is also easier.
+
+Decision
+--------
+
+At the meeting in Berlin (2017-05-30) the attendes decided for "Fractional Unix Time".