Can anybody help me understand the values Yafu is claiming for the difficulty in this example?

Code:

n: 401721424383720426137324949508336187045848565417289917430550907056665790265814883369879394476169080075318675151956526421358049691930517872710129161972339727160629599769770122149882863
# 7^307+6^307, difficulty: 260.29, anorm: 1.30e+037, rnorm: 1.27e+049
# scaled difficulty: 262.29, suggest sieving rational side
# size = 1.218e-012, alpha = 0.000, combined = 1.324e-013, rroots = 0
type: snfs
size: 260
skew: 0.9746
c6: 7
c0: 6
Y1: -4849687664788584363858837602739217760256
Y0: 12589255298531885026341962383987545444758743
...

The actual SNFS difficulty given by these polynomials is 259.445, according to every definition of SNFS difficulty that I've ever seen. So what are "difficulty", "scaled difficulty" and "size" (the second one) supposed to represent here?