Reformat Script in JSL Editor is very helpful to get the code with a formatted structure.

Often it helps to find bugs in the code and to keep the overview.
But sometimes, it's the opposite.
Is there a way to protect code in a specific area from being re-shuffled by Reformat Script?
Names Default To Here( 1 );
dt = Open( "$SAMPLE_DATA/Big Class.jmp" );
dt << Recode Column(
dt:name,
{Map Value(
_rcOrig,
{"ALFRED", "A",
"ALICE", "A",
"AMY", "A",
"BARBARA", "A",
"CAROL", "A",
"CHRIS", "A",
"CLAY", "A",
"DANNY", "A",
"DAVID", "A",
"EDWARD", "A",
"ELIZABETH", "B",
"FREDERICK", "B",
"HENRY", "B",
"JACLYN", //missing
"JAMES", "B",
"JANE", "B",
"JEFFREY","B",
"JOE","B",
"JOHN", "B",
"JUDY", "B",
"KATIE", "B"
},
Unmatched( _rcNow )
)},
Update Properties( 1 ),
Target Column( :name )
);Select only part of your code and then reformat the script
Jarmo's suggestion works well, however one has to reformat syntactically valid JSL

results in reformatting only the selected parts of the code

Hm, syntactically valid JSL code - reformat works if I remove the code in the "protection area". So, the remainder seems to be OK.
I think the actual problem is:
The two pieces of the the code - above and below the protection area have to be syntactically valid JSL code.
i.e. the protection area has to be on highest level - e.g. a whole function.
another example:

You mean: don't select some code around the protection area such that the remaining code gets consistent, then trigger Reformat Script?
Unfortunately, doesn't seem to work 

Good catch.
There is a work around. The
Advanced=>Comment Block
does not change the structure of the code, it simply comments out a highlighted section of code. If you Comment Block, then Reformat the JSL and then highlight and
Advanced=?Uncomment Block
you will achieve your goal