Mesozoic Era
circa - around (roughly)
there is date of death attach to your social social security number
a.d. when used for the date means "in the year of our Lord" anno domine
The date of a letter should always be the date that the letter is sent. If there is a time frame that an authorization will be effective, that time frame should be stated in the content of the letter or a reference line before the start of the letter.
TBA means "To Be Announced." It's probably in reference to a release date, which indicates that something will be released, but the exact release date hasn't be announced.
There's nothing to "discover" about it. It was "invented" by humans as a global standard of date and time reference.
subsequently means happening at a time subsequent to a reference time
To refer it so that one can save time of searching it.
On or about means sometime close to the specific time or date. When an exact time or date is not known, this phrase is often used.
The earliest reference to Burg Vischering is 1271.
'English time' means that the speaker takes the hour it is in London as its reference, when he is abroad. People may do this when they are unsure if you are using the same time reference as them. "The landslide happened at 13:30, English time" = whatever the country one is in, every body has the same time reference and is able to know exactly when the landslide happened.
In a living trust, the phrase 'dtd' stands for dated. It is very important to have the proper date that the trust effective for.