Interesting situation came up last night, and made me realize that there are two very different ways of seeing what constitutes a line on an unlined field. The question in a nutshell: is it right to consider the secondary cones on the sideline (those that signify the depth of the brick mark or the centre of the field) as part of the sideline, or should we just look at the line between the "brightly colored, flexible cones" at the corners of the endzones? What's the consensus?
The following are (as far as I can tell) the only relevant references in the 11th Edition:
III.Playing field: E. The corners of the playing field proper and the end zones are marked by brightly colored, flexible cones.
II.Definitions: J. Line: A boundary defining the playing areas. On an unlined field, the boundary is an imaginary line segment between two field markers with the thickness of said markers. Line segments are not extrapolated beyond the defining markers.