peruslinjat
Peruslinjat is a Finnish term that translates roughly to “base lines” or “baseline lines.” It is not a single fixed technical term in English; its exact meaning varies by field. Generally, peruslinjat refer to lines that function as reference points from which measurements, constructions, or comparisons are made.
The word is formed from perus-, meaning base or fundamental, and linjat, the plural of linja, line.
In surveying, a peruslinja commonly denotes a baseline used to measure distances and to orient subsequent survey
Because peruslinjat is a generic Finnish term, its precise meaning should be inferred from the specific document
See also: baseline, reference line, axis, chart baseline, surveying baseline.