Is this a legal quoted-printable encoding?

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Is this a legal quoted-printable encoding?

a ==
3D b

How about this one?

a = b
the second line

I wonder if = can occur without encoding, and an encoding such as =3D can be put on two lines. The RFC is ambiguous.

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Jaap Joris Vens On

In Quoted-Printable encoding, the = character MUST be encoded as =3D

Here is the relevant excerpt from RFC 2045:

Octets with decimal values of 33 through 60 inclusive, and 62 through 126, inclusive, MAY be represented as the US-ASCII characters which correspond to those octets (EXCLAMATION POINT through LESS THAN, and GREATER THAN through TILDE, respectively).

The = ASCII character has decimal code 61, which explains why this number is explicitly forbidden by the RFC. Therefore, both of your examples are not legal Quoted-Printable encodings. The following encoding is legal:

a =3D b
the second line