Just a slight clarification:
The ranks you get for Hobby and Background don't stack, right? I mean, they both give you +4 ranks in certain skills at 1st level, and the normal limit of 4 ranks at first level applies, so they were never intended to stack? Except of course if you can change Occupations, you could presumably also change hobbies, so once you got to 5th level you could take a background skill as a hobby, provided you hadn't been pumping ranks into it all that time.
On page 27, it says:
Each character receives a number of skills from his character class, modified by her Intelligence. The skills character chooses begin with 4 ranks. As a character rises in level she will receive more skill points to increase skills. The maximum a skill can be trained to is the character’s total level plus three. Cross-class skills (skills a character has no selected) have a maximum value of one-half this number.
This is more vague than you presumably wanted it, and d20 Modern itself is not as clear as I'd prefer either. But even where the old rules are less fuzzy, I don't want to fall back on my understanding of them and miss an important difference meant to be attended to in Modern20. Which of the following does not apply?
1) At 1st level, a character picks a number of Starting Skills equal to the class skill number + Int Mod.
1a) If the skill picked is on the list of class skills for the 1st level class, then that skill will be assigned 4 ranks.
1b) If the skill picked is not on the list of class skills, it may still be selected, but it will only be assigned 2 ranks, since any more ranks would violate the maximum ranks by level rule.
1c) None of the starting skills can be the same as either the Hobby skill or the Background skills, otherwise the maximum skill ranks principle will be violated.
2) There is a maximum number of ranks a character may have in a given skill.
2a) The maximum for class skills is character Level + 3
2b) The maximum for Cross-class skills is (Level +3)/2, rounded down.
2c) The maximum for skills which have been class at some levels and Cross-class at others is (Number of levels as class skill +3) + ((Number of levels as Cross-class skill + 3)/2, rounded down)?
3) There is a maximum number of skill points a player can spend on a skill each level.
3a) For class skills, the number is 4.
3b) For Cross-class skills, the number is 2.
3c) You cannot spend enough points on a skill at a given level that the maximum ranks rule by level would be violated.
4) The Hobby and Background skills selected add ranks to the chosen skills.
4a) If the skill is a class skill at 1st level, then taking it as a Hobby or Background skill adds 4 ranks
4b) If the skill is a Cross-class skill at 1st level, then taking it as a Hobby or Background skill adds only 2 ranks, as any more would violate the level limit on skill ranks.
I realize that it may look like I'm splitting sheep here over what was intended as a bang easy concept, but except for item 3, which is a specification I recall , surely any accurate answer to the question of whether you've spent too many points on a given skill would have to take all of the other points into account.
Also, there is no mention of multi-classing. Is it allowed?