Before 1930 Linköping was divided into four parts, each containing abt. 100 or more blocks. The map Anna-Carin links to shows the north-east part, called S:t Lars kvarter because the S:t Lars church was situated in this part of the town. The church, however, was the parish church in S:t Lars parish, which surrounded the town. The town's parish church was the cathedral.
At the bottom of the page with the map of S:t Lars kvarter there are links to the three other parts: the north-west, S:t Per's kvarter (the cathedral, consecrated to St. Peter, is situated in this part), the south-east, Tannefors kvarter (which got its name because it faced the village Tannefors in S:t Lars parish - the village, on the west of Stångån, has nothing to do with the modern district Tannefors, on the east of Stångån), and the south-west, S:t Kors kvarter (an older cross-roads of sand [sandkorset] was later misinterpreted as Saint Cross).
1 January 1930 the modern system with names given to each block was introduced, but in a way that preserves the old division: all blocks of S:t Per's kvarter were given names beginning with 'A', all in S:t Lars kvarter names beginning with 'B', all in Tannefors kvarter names beginning with 'D' and all in S:t Kors kvarter names beginning with 'E'. As the town grew, the blocks of the new districts were and still are named in the same way (with sometimes peculiar results), why each district has block-names with the same first letter.