In approximate system instability analysis it is common practice to simplify by considering isolated members with end restraints that to some extent reflect the interaction with the surrounding structure. Buthling modes for such isolated members have traditionally been limited to modes that can be associated with positive end restraints. A wider range of realistic buckling modes, that also imply negative end restraints, are reviewed and discussed. Further, approximate formulas for effective length factors and inflection point locations for unbraced (free-sway) and fully braced compression members are developed. The range of applicability of the formulas are identified by comparisons with exact results for a reasonable wide range of positive and negative restraints.