Mapping of timestamp is not clear whether timestamp shall specify only UTC time or whether local time can be used.
Standard merely states "MMS LastModified attribute" which permits either timestamp.
Since there is no 61850 (Ed1) mechanism to map local time to UTC, a client cannot interpret local times using only 61850 mechanisms.
Note: This is the only place in 61850 where "local time" seems to be permitted.
Note: This same issue is relevent to 61850-8-1 : 2011(=Ed2)
Proposal
Change text from:
"The IEC 61850-7-2 LastMOdified attribute shall be mapped tothe MMS file LastModified attribute"
to
"The IEC 61850-7-2 LastMOdified attribute shall be mapped tothe MMS file LastModified attribute using UTC semantics (i.e. with a trailing "Z")"
Discussion
Created
Status
ISO 9506 (MMS) refers to GeneralizedTime as the format for this value. GeneralizedTime is defined in ISO 8824-1 to be the following:
42.3 The type is defined, using ASN.1, as follows:
GeneralizedTime ::= [UNIVERSAL 24] IMPLICIT VisibleString
with the values of the VisibleString restricted to strings of characters which are either
a) a string representing the calendar date, as specified in ISO 8601, with a four-digit representation of the year, a two-digit representation of the month and a two-digit representation of the day, without use of separators, followed by a string representing the time of day, as specified in ISO 8601, without separators other than decimal comma or decimal period (as provided for in ISO 8601), and with no terminating Z (as provided for in ISO 8601); or
b) the characters in a) above followed by an upper-case letter Z; or
c) the characters in a) above followed by a string representing a local time differential, as specified in ISO 8601, without separators.