Greek ELSTAT code

ELSTAT, the Hellenic Statistical Authority, codes the census geography that the 2011 Kallikratis reform created. The length states the tier, and the tiers nest: two digits for one of the 74 regional units, four for a municipality, six for a municipal unit, eight for a community and ten for a settlement. Abeliko is 2301020301, which reads as regional unit 23 Karditsa, municipality 2301, municipal unit 230102, community 23010203, settlement 01.

Regions are numbered in a separate series and carry no code in the census column at all. The three-digit values used for them, such as 351 for Attica, combine a level digit with the region's European statistical code.

Leading zeros are part of every level: 1,253 settlement codes and 41 municipality codes begin with one, so a numeric column loses them.

How far a code can be trusted depends on its tier. The two-digit regional unit codes have not moved: all 75 are identical in the 2011 and 2021 censuses. Below that they are reused. Within each parent the seat keeps 01 and the others are ordered alphabetically in Greek, so adding or removing one unit shifts every code after it. Between those two censuses 35 municipality codes changed hands, 5202 passing from Hydra to Agkistri, and 975 of 12,086 settlement codes came to name a different place, roughly one in twelve. A code below the regional unit tier is only meaningful alongside its census year, and names do not settle the ambiguity either, since two distinct settlements can share one.

Kallikratis recoded everything rather than renumbering it. Of the 7,690 settlements that appear under both the old and the new scheme, none kept its code, and the old Attica codes were not even numeric. A value from before 2011 belongs to a different system, not to an earlier version of this one.