If it's just spaces, then you can use 

/AB\s*CDE/

[download]

But if they can be any characters except the sequence CDE, you can use 

/AB(?:(?!CDE).)*CDE/s

[download]

(?:(?!PAT).)* is to PAT as [^CHAR]* is to CHAR.

In reply to Re^2: regular expression inverse match NOT match? by ikegami
in thread regular expression inverse match NOT match? by virtuemart2

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