Act of Congress dated February 11, 1805, 2 Stat. 313, 43 USC 752
The boundaries and contents of the several sections, half-sections, and quarter-sections of the public lands shall be ascertained in conformity with the following principles: First.
All the corners marked in the surveys, returned by the Secretary of the Interior or such agency as he may designate, shall be established as the proper corners of sections, or subdivisions of sections, which they were intended to designate; and the corners of half- and quarter-sections, not marked on the surveys, shall be placed as nearly as possible equidistant from two corners which stand on the same line. Second.
The boundary lines, actually run and marked in the surveys returned by the Secretary of the Interior or such agency as he may designate, shall be established as the proper boundary lines of the sections, or subdivisions, for which they were intended, and the length of such lines as returned, shall be held and considered as the true length thereof.
And the boundary lines which have not been actually run and marked shall be ascertained, by running straight lines from the established corners to the opposite corresponding corners; but in those portions of the fractional townships where no such opposite corresponding corners have been or can be fixed, the boundary lines shall be ascertained by running from the established corners due north and south or east and west lines, as the case may be, to the watercourse, Indian boundary line, or other external boundary of such fractional township.
Third. Each section or subdivision of section, the contents whereof have been returned by the Secretary of the Interior or such agency as he may designate, shall be held and considered as containing the exact quantity expressed in such return; and the half sections and quarter sections, the contents whereof shall not have been thus returned, shall be held and considered as containing the one-half or the one-fourth part, respectively, of the returned contents of the section of which they may make part.
You previously said: "I have yet to read a section in the BLM Manual that fences can only be accepted if in fact they were at the origianal PLSS corner. Maybe you could point that out?"
1973 Manual 6-15. The position of a tract of land, described by legal subdivisions, is absolutely fixed by the original corners and other evidences of the original survey and not by occupation or improvements, or by the lines of a resurvey which do not follow the original.
2009 Manual 5-29. The position of a tract of land, described by legal subdivisions, is absolutely fixed by the original corners and other evidences of the original survey and not by occupation or improvements unrelated to the original survey or by the lines of a resurvey that do not follow the original as faithfully as possible for the time.
4. Surveys of Public Lands: Generally
A landowner’s bona fide belief concerning the boundary between his land and public land is not the same as a bona fide right that must be protected in a resurvey under 43 U.S.C. § 772 (2006). Although a person may have a bona fide belief based on an understanding of where a boundary lies, a bona fide right within the meaning of the statute must be based on good faith reliance on evidence of the original survey.
This was discussed on the other forum extensively: http://surveyorconnect.com/index.php?mode=thread&id=59273#p59431
The entire "Resurvey Act" is posted here. Maybe examining the legislative history can shed some light on Congress' intent.
FINAL BILL, SIXTIETH CONGRESS, SESSION II (pg. 845)
CHAP. 271- An Act Authorizing the necessary resurvey of public lands.
Be it enacted by the Senate and House of Representatives of the United States of America in Congress assembled, That the Secretary of the Interior may in his discretion cause to be made, as he may deem wise under the rectangular system now provided by law, such resurveys and retracements of the surveys of public lands as, after full investigation, he may deem essential to properly mark the boundaries of the public lands remaining undisposed of: Provided, That no such resurvey or retracement shall be so executed as to impair the bona fide rights or claims of any claimant, entryman, or owner of lands affected by such resurvey or retracement: Provided further, That not to exceed five percent of the total annual appropriation for surveys and resurveys of the public lands shall be used for the resurveys and retracements authorized hereby.
Approved, March 3, 1909.
The term "bona fide belief" is also discussed in the '09 manual
I don't think its all that new of a term or concept.