120 spacing was for 5 and ultra 6 freewheels.
126 spacing was for standard 6 and ultra 7 freewheels and cassettes on road bikes. All of the 7 speed stuff was about 5.0 spacing - Shimano and Suntour.
130 was for 8 and greater speeds, but some cheaper bikes still came with 7, but in 130 spacing.