Max_nobs in LETKF

What is the meaning of this parameter in LETKF yaml?

“max nobs” limits the number of observations used in the local area.
LETKF searches for all local observations within lengthscale from a grid point (lengthscale is specified in yaml). If “max nobs” is specified in yaml, the number of local observations used in the assimilation is limited to be not greater than “max nobs” (i.e. only the closest “max nobs” obs would be used, if there are more local obs than that limit).