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- "now" which always resolves to the current time,
- "now-XXX" where XXX can be a standard qualifier like "1d", "4d", "1w", etc: a period relative to now.
- "midnight" which always resolves to midnight of the previous day
- "midnight-XXX" where XXX can be a standard qualifier like "1d", "4d", "1w", etc: a period relative to last midnight.
- any Unix time (ie milliseconds after "Jan 1 00:00:00 1970"),
- and the following date/date-time formats: "yyyy'-'DDD", "yyyy'-'M'-'dd", "yyyyMMdd", "dd MMM yyyy", "dd MMM yy", "MM/dd/yy", "MM/dd/yyyy", "MM.dd.yy", "MM.dd.yyyy", "dd MMM yyyy hh:mm:ss", "yyyy-MM-dd" (ISO Date), "yyyy-MM-ddZZ" (ISO Date-Timezone", "yyyy-MM-dd'T'HH:mm:ssZZ" (ISO DateTime-Timezone), "EEE, dd MMM yyyy HH:mm:ss Z" (SMTP DateTime).
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