Name of the Model Specification File. Must be the first option. Filename may not contain embedded spaces. If it contains commas, semicolons, or parentheses, then it must be surrounded by single quotes ' or double quotes ". Filename may also contain equal signs if it is enclosed in quotes. If filename is the same as any option of the $MSFI record, it must be enclosed in quotes. Filename may contain at most 71 characters.

NORESCALE: if a search is continued, it is continued just as it would have been in the previous run. This option has no effect if the Estimation Step is not implemented or if the step is implemented, but using different options on the $ESTIMATION record from those used with the previous run. This is the default option.

RESCALE: the search is to be restarted with initial estimates taken to be the final estimates from the previous run, so that a UCP value of 0.1 now corresponds to a final estimate from the previous run. This option may be used only if the search with the previous run terminated successfully and all the options used on the $ESTIMATION record coincide with those used with the previous run (except the MAXEVAL option).

If the data are to be understood to be population data, the option NPOPETAS may be needed, and then the part "=n", n>0, may also need to be coded. The integer n should be the number of population eta variables. The part "=n" is required when the $ERROR block describes a model that changes the value of F, and there is no $PK block. It is also required when variables A(n) are used in the $PK abbreviated code. If the data are to be understood to be single-subject data, the option NPOPETAS=0 may be needed.

May also be coded POPETAS.

This option should be used if and only if the model specification file is being used to convey prior information to a succeeding problem in the control stream (See TNPRI). No task records may appear in a problem specification containing a $MSFI record with this option.

When the $MSFI record is used in a problem specification, $THETA, $OMEGA and $SIGMA records should not appear in that specification. It is permissible for the data file to differ from the original data file, but usually this is not done.

MSFTEST: prevents an MSF file from being utilized in a subsequent control stream file or problem if there were errors. This is the default.

NOMSFTEST: sometimes the MSFI error check is too strict. This occurs particularly when using classical NONMEM methods. To turn of MSFI error checking, use NOMSFTEST.

Read in MSF files from previous versions. With NONMEM 7.5.0, choices are:

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  $MSFI filename.msf VERSION=7.4.0
  $MSFI filename.msf VERSION=7.3.0
  $MSFI filename.msf VERSION=7.2.0
  $MSFI filename.msf VERSION=7.1.2
  $MSFI filename.msf VERSION=7.1.0
  $MSFI filename.msf VERSION=6.2
  $MSFI filename.msf VERSION=6.1

The MSF file format for NONMEM v7.5.0+ does not require a VERSION specification. They are to be used by NONMEM v7.5.0+.

When the problem that created the MSF file has successfully completed, calling for a resumed or new estimation is prevented when the method is FO/FOCE/Laplace. To allow analysis to continue, or to allow an analysis on a new data set, resuming from the final parameters of the MSF file, use the option NEW.

With NONMEM 7.3 and later, when MSF or MSFO option is used to specify an MSFO file in the $EST record e.g.,

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 $EST ... MSFO=msfroot.msf

then in addition to the main MSF file msfroot.msf, file msfroot_ETAS.msf containing individual ETAs will also be produced, and provide additional information when a $MSFI record is used in a subsequent problem or control stream. This is referred to as an "extra" msf file. If the Covariance Step is also implemented, files msfroot_RMAT.msf and msfroot_SMAT.msf containing intermediate information on the R matrix and S matrix will also be produced. These files provide information when a $MSFI record along with a $COV ... RESUME record is used in a subsequent problem or control stream.

The use of an extension, e.g., .msf, is optional. If the _ETA file is not present, NONMEM issues a warning:

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 WARNING: EXTRA MSF FILE COULD NOT BE OPENED: c5msf2x_ETAS

There is no warning if _SMAT and/or _RMAT are not present.