IsCDLeft returns true if b is part of Content-Disposition header line cut from left.

IsCDRight returns true if b is part of Content-Disposition header line cut from right.

IsCTFull returns true if b in Content-Type header line.

IsCTLeft returns true if b is part of Content-Type header line cut from left.

IsCTRight returns true if b is part of Content-Type header line cut from right.