There are established a standard for how the most common information should be abbreviated. There are also a set of special signs that is very common to use when you are registering.

Abbreviations

Sex
m  male
k   female

Residental status
b   permanent resident
mt  temporarily resident
f     absent
Household status
hf   male head of family
hm  female head of family
s   son
d   daughter
tj   servant
fl   lodger, belonging to the household, but not necessarily a relative
el  single lodger, making his/her own food
b   visitor

Marital status
g   married
ug  unmarried
e  widow/widower
s  separated
f   divorced

Place of birth
t   born in the district of registration
'Undersåtlig forhold' (citizenship)
n   Norwegian citizen
Nationality/Ethnic grouping
n   Norwegian
l   Lappish/Sami
lf  Lappish, permanent residential
ln  Lappish, nomadic
k  Kvensk (ethnically Finnish)
b  mixed
Language
n   Norwegian
l   Lapp/Sami
f   Finnish ('kvensk')

Special signs

??   signifies that the handwriting in the original is indistinct or illegible (e.g. 'Kristi??')
 
@   is used as a separator between two alternative readings of the original when it is impossible to decide which is the correct one (e.g. 'Even@Sven')
 
%   indicates stricken out text in the source. If a word or a sentence is stricken out it is marked with a % in front and behind the stricken out word (e.g. 'Peder%Hans%')
 
!!   siginifies that this information in the source must be wrong for obvious reasons (!! alone in a field means that the information is missing)
 
*   after a piece of information, e.g. a surname, indicates that the information is not given in the original, but included by the registrator on the basis of the information regarding the surrounding persons in the source
 
E:   indicates that the following note is that of the registrator and not to be found in the source