I don't know how confusing this gets to be (if it ever gets to be confusing) but here is a little blurb to help demystify the caste system. The hierarchy (as I'm sure you realize) works this way:
Low Income/Middle Income Townsman
From the family tree:
The Simcity Caste System was codified in December of 1915. It was ratified by the House of Lords at Ethelden Palace on June 3, 1916 and went into effect on April 15, 1917. All persons born on or after this date were assigned castes in accordance with their birth (leisure or labor), occupation and household finances. All born into the labor class were assigned the caste of "Townsman". This term was chosen as a neutral descriptor for the poor, who by enlarge lived in urban settings due to the industrial boom. Previously, laborers were assigned limited voting rights dependent upon their performance on a written examination. 83% of the labor class did not have the ability to read or write in 1917, a percentage that remained fairly constant between The Local Polity Act of 1854 (which allowed for local governments elected by the people) and the ratification of The Social Partitioning Act that made the caste system law.
Full Caste Residents are at least 3rd generation Residents (of whatever area they live in) whose parents are both high or full caste. If a person is born full caste then they will always be considered full caste. No matter what you do or whom you marry, you will always be full caste. There is no room to move about the cabin.
High Caste Residents can have any number of generations under their belts and their parents can have been any caste. In some rare instances, even someone who was born a Townie can be considered high caste (JL's parents, for example). Money is the big determining factor here. Secondary to that is marriage. Occupation can also play a role in whether or not a person is considered to be high caste. If you head a big company (like Dina does) or you're just generally a hot-shot professional (like Troy) then this is a big leg up towards being considered high caste, regardless of what you were born.
Mid Caste Residents are generally Residents that make a modest wage and live comfortably. This is the widest, most open caste and contains Residents from all sorts of family backgrounds. From a social point of view, this is probably the most ideal position that a person can occcupy. Mid caste Residents live well and don't have to worry about the social pressures of the elite or the economic hardships of the poor. A mid caste Resident can basically marry whomever she wants to. If they choose to marry someone of a lower class then no one shuns them. If they decide to marry someone of a higher class, then they are most always accepted into the fold. They are for the most part well-educated and can pursue whatever occupation they want to. A win/win situation.
Low Caste Residents are low-income Residents. Most of them are Townie-born though some families (like the Brokes) have been around for many generations.
Townsmen are not Residents at all. Before the caste system, there were only two classes of people- Labor and Leisure. The Townsmen (or Townies) are the descendants of the Labor class. They live in segregated enclaves. Most of them work for very minute wages. They do not have the legal right to vote, hold property, work in public office or marry (unless they are very lucky and a Resident wishes to marry them). Their children attend the same schools as the Residents but are taught in separate classrooms. They go to the same hosipitals but are often denied care (if a Resident has need, regardless of the urgency of that need, then they are always given preference). Socially, they are not even supposed to stare at a Resident too hard, let alone talk to the Residents.
A Townsman can become a Resident if one of the following conditions is met:
1) A Resident will testify in court to the fact that the Townsman is his son/daughter. Nowadays, this is also subject to a DNA test. Many Townsmen do have Residents for biological fathers but their fathers would never in a million years claim them publically.
2) If it is proven that a Townsman is the son/daughter of a Resident and that Townsman is a minor (under the age of 14) then his/her mother is also elevated to Resident status. This is what happened to Troy's mother.
3) If a Townsman marries a Resident, then that Townsman is automatically elevated to Resident status.
4) If a Townsman lives at a Resident's address for 5 years, then that Townsman is elligible to become a Resident. This happens most frequently to boarding house tennants like Jack. But it also happens to live-in maids and nannies like Haven's mother.
5) If a Townsman lives at a Resident's address for 3 months, various prominant Residents give character references in court and certain hefty terrifs are paid, then that Townsman can become a Resident. This last one is often done on the sly. Not a common practice and even though it is perfectly legal, it is normally seen as being a little shady. This is what happened to the Bennett family that works and lives at Tellerman Farm.
And I know I said that I wouldn't be online while I was away but I just couldn't help myself. :p