Regular Expressions 101

Pro

Non-Capturing Group(?:^(?:(?!\bItem\b.)*)See\b.*|((?<=\D)Item.+?1A.+?Risk Factors(?=\D).+?(?=Item 1B|$)))

1st Alternative^(?:(?!\bItem\b.)*)See\b.*

^start of line

Non-Capturing Group(?:(?!\bItem\b.)*)

Negative Lookahead(?!\bItem\b.)*

*repeats the group contents below any number of times:

\ba Unicode word boundary

Itemthe literal text Item (case sensitive)

\ba Unicode word boundary

.any Unicode character (except for line terminators)

Seethe literal text See (case sensitive)

\ba Unicode word boundary

.*any Unicode character (except for line terminators), repeated any number of times

2nd Alternative((?<=\D)Item.+?1A.+?Risk Factors(?=\D).+?(?=Item 1B|$))

Group 1((?<=\D)Item.+?1A.+?Risk Factors(?=\D).+?(?=Item 1B|$))

Positive Lookbehind(?<=\D)

\Dany character that is not a Unicode decimal digit

Itemthe literal text Item (case sensitive)

.+?any Unicode character (except for line terminators), repeated at least once

1Athe literal text 1A (case sensitive)

.+?any Unicode character (except for line terminators), repeated at least once

Risk Factorsthe literal text Risk Factors (case sensitive)

Positive Lookahead(?=\D)

\Dany character that is not a Unicode decimal digit

.+?any Unicode character (except for line terminators), repeated at least once

Positive Lookahead(?=Item 1B|$)

1st AlternativeItem 1B

Item 1Bthe literal text Item 1B (case sensitive)

2nd Alternative$

$end of line

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

(?:^(?:(?!\bItem\b.)*)See\b.*|((?<=\D)Item.+?1A.+?Risk Factors(?=\D).+?(?=Item 1B|$)))

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