I know that, i'm just trying to paint a picture without being to padantic. And as for you saying it's of the highest external mark... That's wrong. Alot more complicated than that.
It's not.
The top exam mark earned by your cohort will be the top internal mark awarded to your school cohort and the bottom exam mark will be the bottom internal mark awarded to your school cohort. The exams are what are used to set the top and bottom marks and the total marks earned by the school cohort in the exam will also match the total marks available for the internals.
Top exam mark = 98 therefore top internal mark will also be 98.
Bottom exam mark = 60 therefore bottom internal mark will be 60.
Then the total marks are added up - say 1187 - then there are 1187 marks for the cohort for internals (give or take a mark) based on ranks and gaps.
Your example was wrong as you didn't link the internal moderated marks to the exams and they are very much linked. They have to be as the HSC is the only common task so it is the only task that can be used to moderate the state and the schools across the state.
If School A sends in 98, 99 and 100 and School B sends in 60, 61 and 62 but both schools exam marks are 89, 90, 91 guess what - both schools end up with the same marks as it shows School A marked too easy and School B marked too hard but the exam results say that the cohorts are of equal ability.
There are the odd exceptions such as when the top internal student totally stuffs up their exam and say is sent in with 95, with second at 93 but the 95 student gets 40 on the exam then that mark would be removed from the moderation process as it is an anomoly and would skew that school's internal results (the student who earnt 40 in the exam would still keep that mark as their exam mark but it wouldn't impact the rest of the class's moderated school assessment marks). This happens for any odd result that doens't fit with the general construction of the class that is sent in.
The other exception would be if two or more students are sent in with equal first because then they average the top 2/3 marks depending on how many were ranked equal first e.g. two equal firsts sent in - one gets 98 in the exam and the second exam mark is 88 - the two equal firsts get the average of 98+88=93 as their internal.