Τηνthe literal text Την (case insensitive) \s?optionally matches a Unicode whitespace character
Comment: matches Την with a possible space afterwards
Group KEK_date(?P<KEK_date>\d{2}/\d{2}/\d{4}) \d{2}a Unicode decimal digit, repeated exactly 2 times
/the literal / (4710 / 578 / 2F16)
\d{2}a Unicode decimal digit, repeated exactly 2 times
/the literal / (4710 / 578 / 2F16)
\d{4}a Unicode decimal digit, repeated exactly 4 times
Comment: matches a date of the given format and captures it with a named group
.+any Unicode character (except for line terminators), repeated at least once
Comment: Allow for an arbitrary sequence of characters
Non-Capturing Group(?:κωδικ.\s?αριθμ.\s?καταχ.ριση.|κ\.?α\.κ\.:?) 1st Alternativeκωδικ.\s?αριθμ.\s?καταχ.ριση. κωδικthe literal text κωδικ (case insensitive) .any Unicode character (except for line terminators)
\s?optionally matches a Unicode whitespace character
αριθμthe literal text αριθμ (case insensitive) .any Unicode character (except for line terminators)
\s?optionally matches a Unicode whitespace character
καταχthe literal text καταχ (case insensitive) .any Unicode character (except for line terminators)
ρισηthe literal text ριση (case insensitive) .any Unicode character (except for line terminators)
2nd Alternativeκ\.?α\.κ\.:? κthe literal κ (95410 / 16728 / 3BA16) (case insensitive)
\.?optionally matches the literal . (4610 / 568 / 2E16)
αthe literal α (94510 / 16618 / 3B116) (case insensitive)
\.the literal . (4610 / 568 / 2E16)
κthe literal κ (95410 / 16728 / 3BA16) (case insensitive)
\.the literal . (4610 / 568 / 2E16)
:?optionally matches the literal : (5810 / 728 / 3A16)
\s+a Unicode whitespace character, repeated at least once
Comment: defines two lookaheads, either of which suffices
Group KEK_number(?P<KEK_number>\d+) \d+a Unicode decimal digit, repeated at least once
Comment: captures a sequence of numbers
g modifier: global. Finds all matches instead of stopping after the first
m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string
i modifier: insensitive. Matches without distinguishing uppercase and lowercase letters
x modifier: extended. Ignores unescaped whitespace and comments outside character classes