The restart files from ECLIPSE are organized by keywords, which are of three different types:

1. Keywords containing the dynamic solution, e.g. pressure and saturations.
2. Keywords containing various types of header information which is needed for a restart.
3. Keywords containing various types of diagnostic information which is not needed for a restart.

Keywords in category 2 and 3 are referred to as static keywords. To be able to restart ECLIPSE, the ERT application has to store the keywords in category 2, whereas keywords in category 3 can safely be dropped. To determine whether a particular keyword is in category 2 or 3 ERT considers an internal list of keywords. The current list contains the keywords: `
INTEHEAD LOGIHEAD DOUBHEAD IGRP SGRP XGRP ZGRP IWEL SWEL XWEL ZWEL
ICON SCON XCON HIDDEN STARTSOL PRESSURE SWAT SGAS RS RV ENDSOL ICAQNUM ICAQ IAAQ
SCAQNUM SCAQ SAAQ ACAQNUM ACAQ XAAQ
ISEG ILBS ILBR RSEG ISTHW ISTHG
` Here you can dynamically add to this list. The magic string `__ALL__` will add all static keywords, but use of this option is strongly discouraged, as it wastes a lot of disk space.