Tidal data question

[CJ1]

I apologise in advance for such a basic question, but can someone give me the meaning of the data given in Reeds almanac alongside the “TIDE” section just below each port entry. For example, under the port of Rye it says:
“TIDE: ML 2.0; duration 3.25hrs sp, 5hrs nps”

Whereas under the entry for Burnham on Crouch it says:
“TIDE: ML 2.5; duration 0610”

I suppose ML is the overall average height of tide across all states of tide.

But I don’t know what “Duration” refers to, or why it is expressed sometimes as “hrs” and sometimes as an actual time.

Help From people more knowledgeable than I would be appreciated.

 

[LittleSister]

According to the 'Tides' chapter in an old Reeds I have at home -

ML = Mean Sea Level = The average level of the sea surface over a long period, preferably 18.6 years.

Duration = The time between Low Water and the next High Water, normally slightly more than 6 hours. It can be used to calculate the time of Low Water when only the High Water time is known.

I think the 0610 is not an actual time but a period, and that it will be approximately the same for springs and neaps, in contrast to the Rye example which has very different durations depending on whether springs or neaps..

 

[CJ1]

Thank you !