dnd 5e – Is "all targets must be within a diameter of unit X (circle)" equivalent to "all targets must be within X units with each other"?

Several spells, or higher level spell versions, have a language like this (charm person At higher levels from the Player's manual):

Creatures should be at a distance of 30 feet from each other when you point them.

I think the above statement is equivalent to "The creatures must be within a 30-foot diameter (ie, a radius of 15 feet)."

When we play with such spells and use figurines and rugs, I and others sometimes begin to measure distances between pairs of targets, instead of simply dropping a circle template 30 feet in diameter to see if everyone can fit inside.

Am I understanding correctly, and Are the two phrases of my title exactly equivalent?

Note 1: I understand the difference between pointing to an area of ​​effect, such as a circle or sphere, and targeting specific creatures within an area.

Note 2: Similar language appears in other editions, for example. heal mass minor injuries since Player's manual v3.5: "One creature / level, two of which can not be more than 30 feet away."

dnd 5e – Can the "permanent teleportation circle" be dispelled?

Yes. It can dissipate.

As Jeremy Crawford indicates here.

If the effect of a spell becomes permanent, it can be dissipated,
unless your description says otherwise.

Then, unless a description of the spell says otherwise, it is still an effect of the spell and dispel magic Finish the spells.

Several reasons may arise to discourage someone from dispelling a Teleportation Circle they encounter.

  1. They want more options to travel (noting the address for
    later use).
  2. The agreement of the gentlemen not to mess with the work of others on that scale (because magicians, especially, know how much it cost).
  3. Surveillance of the comings and goings of certain individuals.

This does not change the fact that by RAW can dissipating only decreases the likelihood that they will.