Umm... I assume that the "any strings" of fields 1 and 3 cannot contain spaces? Otherwise we are in real trouble... how can you distinguish between spaces that are record seperators and those that are in the string?

Example:

Foo 23 45 Bar _$string1
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This could be parsed into the array ('Foo', 23, '45 Bar', '_$string1') or into the array ('Foo 23', 45, 'Bar', '_$string1')...