How the Marauders Map works...explains problems

[merimom3]

No: HPFGUIDX 39933

I don't claim to know all about it (having not yet completed my 
course of study at Hogwarts ;-), but it seems to me that the Map has 
to work in one of two ways.

1.  It shows everybody within its range, all the time
2.  It only shows what you need at the time

If it is 1, then most of the time the Map is consulted, most of the 
people - in classrooms, the Great Hall, dorms - are in such 
concentrations that the little tiny characters and words would be 
impossible to decipher.  I mean, imagine twenty little ink figures 
with twenty names in a classroom, all written atop one another in a 
big jumble.  So your eye would naturally go to any that were moving 
and/or alone, which covers all the known instances IIRC (correct me 
if I'm wrong).

If it instead works as in 2, rather conveniently only showing what 
is needed for the plot, it requires some mechanism, some rule on 
which to operate that, IMHO, can only be explained as...wait for 
it...magic!  "Perhaps you are only able to see people whom you have 
previously met/seen *or* interacted with", the rule that Heidi put 
forward, doesn't work IMO because Harry has "interacted" with a very 
many people who are on the grounds at one time.

Perhaps it is simply a matter of our human eyes searching for 
anomalies - who's that way over there? is there anyone near where I 
am now? are there any unfamiliar/unexpected names?

On a tangent, my personal definition of magic is "anything that 
can't be explained", which gives Jo as much leeway as she wants and 
covers a multitude of FLINT-like occurences, while I just sit back 
and enjoy the ride.

Ginny