Regular Expressions 101

Explanation
Pro

Positive Lookbehind(?<=\sRechnungsbetrag\s$inklusive Umsatzsteuer$)

\sa Unicode whitespace character

Rechnungsbetragthe literal text Rechnungsbetrag (case sensitive)

\sa Unicode whitespace character

\(the literal ( (40₁₀ / 50₈ / 28₁₆)

inklusive Umsatzsteuerthe literal text inklusive Umsatzsteuer (case sensitive)

\)the literal ) (41₁₀ / 51₈ / 29₁₆)

\sa Unicode whitespace character

Group asd(?P<asd>\d{1,})

\d{1,}a Unicode decimal digit, repeated at least once

.?optionally matches any Unicode character (except for line terminators)

Group fgh(?P<fgh>\d{1,})?

?repeats the group contents below at most once:

\d{1,}a Unicode decimal digit, repeated at least once

Global pattern flags

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

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25 tokens

(?<=\sRechnungsbetrag\s\(inklusive Umsatzsteuer\))\s(?P<asd>\d{1,}).?(?P<fgh>\d{1,})?

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