Matching nRF Connect SDK releases and Zephyr branches

[Louis]

Up to now I referred to the name of the tag from the west manifest to know the zephyr release. So I assumed that the v2.7.99-ncs1-1 tag was from the zephyr 2.7 branch until I came across a breaking change (timeout from the v2.7.99-ncs1-1 tag is defined in microseconds where it is defined in milliseconds on zephyr's 2.7 branch). Is there a straightforward way to know which zephyr release matches a given nRF Connect SDK release? The nRFConnect SDK 1.9 release notes state that :

The current nRF Connect SDK main branch is based on revision 45ef0d2 of Zephyr, which is located between v2.7.0 and v3.0.0 of Zephyr.

which I assumed meant up to v3.0.0 non inclusively so somewhere on the 2.7 branch but that does't seem to be the case. 

[Louis]

On a wider scope, how does the LTS notion applies to nRF Connect SDK? This post leads me to think that if there are LTS releases, they are not necessarily related to zephyr LTS releases and I couldn’t find any mention of LTS through the different nRF Connect SDK release notes.
On the other hand, this webinar (10:57) refer to LTS releases as if they applied to nRF Connect SDK and the 1.8 release notes refer to the 2.7 branch of zephyr as opposed to the other release notes who refer to specific or a range of tags.