CRROSCC : NAHHTVVDDADDS : DATTRR : ANN...being translated by the National Museum as “The cross of Nectudad, daughter of An...”
If they're right, then Nectudad certainly sounds like it could be a feminine version of Nectan. So even if "dattrr" is Norse in origin, it still seems likely we are dealing with a Pictish name here. I think there are other reasonable ways one could standardize the name, such as Nechtudad or Nachtudad, but I would recommend consulting someone more versed in ogham than I.
Of course, the Norse usually put “daughter” as a tag at the end of the father's name, for instance Kolla Sveinsdóttir as “Kolla daughter of Sveinn” which would give us instead Crosc daughter of Nectudad, with “ann-” beginning some other part of the inscription. I believe the combination of the similarity of croscc and cross and the other neighboring languages that use an X daughter of Y format combine toward making “Nectudad” rather than “Crosc” the daughter in question.
On the other hand, “dattrr” need not be of
Norse
 origin at all, but may come into Pictland through Gaelic or even from 
earlier Celtic languages parallel to its cognate in Gaelic. There are “a
 series of Gaelic names for women beginning with the element Der-/Dar- 
which has been shown to be a Gaelic cognate of the English word 
'daughter', derived from a reduced form of the Proto-Gaelic *ducht(a)ir.
 A close cognate of this word, a derivative of the Indo-European word 
for 'daughter' (the English word is itself a descendant of the Germanic 
derivative), has now been attested in the continental Celtic language 
Gaulish as duχtir...In the inscription, χ= /χ/” (Clancy “Philosopher 
King”). Given these early and widespread cognates, it is not beyond 
possibility that “dattrr” could be a rendering of a Pictish term for 
“daughter” or “daughter of,” though we know so little of the Pictish 
language that this must remain mere speculation.Selected Bibliography:
Clancy, Thomas Owen. “Philosopher-King: Nechtan mac Der-Ilei” The Scottish Historican Review, Vol. LXXXIII, 2. Oct. 2004. pp125-49.
See also Royal Irish Academy, Dictionary of the Irish Language (compact edn, Dublin. 1983), under der.
M.A. O'Brien, 'Der-, Dar-, Derb-in female names', Celtica, iii (1956), 178-9.
E. Hamp. '*dhugHter in Irish', Münchener Studien zur Sprachwissenschaft, xxxiii (1975), 39-40.
National Museum of Scotland
(This is a re-post from 2010. I would now have more to add to--and perhaps subtract from--it. I will include it for now, however, rather than omit it and will hope to offer a revision in the not too distant future.)