Explanation 28x28 magic square
The 28x28 magic square is an odd multiple of 4. A Franklin panmagic 28x28 square does not exist (a Franklin [not pan]magic square can be constructed with help of computer programming).
Methods to construct the 28x28 magic square are:
The medjig magic square gives a simple 28x28 magic square.
Composite simple gives a panmagic 28x28 square.
Composite AxB compact, composite Matroesjka, composite proportional (1)a, 26x26 in 28x28 and concentric are 'specials'
Symmetric transformation and basic key method (ultra magic) leads to ultra magic 28x28 squares.
The remaining methods lead to most perfect magic 28x28 squares.