- * Converts @time_ into an ISO 8601 encoded string, relative to the
- * Coordinated Universal Time (UTC).
+ * Converts @time_ into an RFC 3339 encoded string, relative to the
+ * Coordinated Universal Time (UTC). This is one of the many formats
+ * allowed by ISO 8601.
+ *
+ * ISO 8601 allows a large number of date/time formats, with or without
+ * punctuation and optional elements. The format returned by this function
+ * is a complete date and time, with optional punctuation included, the
+ * UTC time zone represented as "Z", and the @tv_usec part included if
+ * and only if it is nonzero, i.e. either
+ * "YYYY-MM-DDTHH:MM:SSZ" or "YYYY-MM-DDTHH:MM:SS.fffffZ".
+ *
+ * This corresponds to the Internet date/time format defined by
+ * [RFC 3339](https://www.ietf.org/rfc/rfc3339.txt),
+ * and to either of the two most-precise formats defined by
+ * the W3C Note
+ * [Date and Time Formats](http://www.w3.org/TR/NOTE-datetime-19980827).
+ * Both of these documents are profiles of ISO 8601.
+ *
+ * Use g_date_time_format() or g_strdup_printf() if a different
+ * variation of ISO 8601 format is required.