The head of NP is usually a N, NPR, PRO, or substantivized other category (ADJ, D, NUM, Q, VB, etc).

There are many subtypes of NP. Other than the basic grammatical functions, distinguishing different types of NP can be tricky. Here we cover the various types of predicates, NP complements of heads other than verbs, time expressions, and adjunct NPs.

Bare NP is used only for:

• the object of a preposition,
• or the moved accusative subject of an ACI.

• NP-SBJ is used for subjects (always nominative except in ACI constructions), and for nominative NPs in fragments, e.g. in chapter titles and stage directions:
  ((FRAG (NP-SBJ (N Gespraech) (PP (P Zwischen) (NP (ONE einem) (ADJ Catholischen) (CONJ vnd) (ADJ^D^SG Lutheraner)))) (. .))
• Imperatives do not need NP-SBJ, but may have one, e.g. when there is a floating quantifier:
  (VBI^2^PL seht) (NP-SBJ (Q^N^PL alle))

• NP-OB1 is used for the sole object of a verb (regardless of case). In ditransitive verbs, -OB1 is the thing (usually accusative or genitive) and -OB2 is the person (usually dative).  Some tricky verbs like lehren are treated under individual words.
• NP-OB2 is the second of two objects. If a CP-THT is semantically the first argument of the verb (e.g. with verb of saying), the dative argument should be tagged NP-OB2.  Because datives can be ambiguous between arguments and adjuncts (benefactive, possessive, ethical dative, etc.) we tend to treat all clausal datives as either NP-OB1 or NP-OB2, eschewing NP-ADT for these. (If the dative is unambiguously possessive AND both -OB1 and -OB2 are already used in the clause, one can use NP-POS; we do not utilize NP-DPS.)
  
• NP-VOC for vocatives. Note that if an NP contains both a personal pronoun and a noun, NP-PRN is called for: (NP-VOC (PRO du) (NP-PRN (ADJ kleines) (N Kind)))

• NP-PRD and ADJ-PRD are frequently the complement of copulas (sein, werden, bleiben, heißen, also kosten, dünken, wiegen, stehen, liegen, sitzen, wachsen). In such cases the subject is NP-SBJ.
  
• However, if you have expletive es followed by a non-copula and the actual subject, use NP-SBJ-X for the expletive, coindexed with the real subject NP-X. This is most obvious when the verb doesn't agree with es: 
  (IP-MAT (NP-SBJ-X (EX^N^SG Es)) (VBPI^3^PL wonen) (NP-X (N^N^PL Portugaleser))...
• Similarly, NP-SBJ-X is used when there is a subject dass- clause or subject infinitival:
  (IP-MAT (NP-SBJ-X *exp*) (IP-INF-X (NP-OB1 gottz gelubt) (VB tuon)) (RDPI wirt) ... (VBN geraten))
(IP-MAT (NP-SBJ-X (EX es) (BEPI ist) (ADJP-PRD (ADJ mühsam)) (IP-INF-X (NP-OB1 weisheit) (RP nach) (VB stellen)))
  
• The null expletive is (NP-SBJ-X *exp*), expletive es is (NP-SBJ-X (EX^N^SG es)), and expletive das is (NP-SBJ-X (D^N^SG das)).

• NP-PRD is usually nominative but may be genitive (in which case don’t follow the CHLG practice of putting genitive NP-POS inside an empty NP-PRD) or even dative:
  (RDDI wurden)  (NP-SBJ (PRO^N^PL wir))  (NP-PRD (N^G^SG sins)) 'we were of a mind'
  (NP-SBJ (N^N^SG rum)) (RDPS werde) (NP-PRD (D^D^PL den)) 'praise be to those'
  
  
• NP-SMC is the secondary predicate of an object (in a 'small clause'), frequently with verbs like nennen (X names Y Z), ditransitive heißen (X calls Y Z), machen (X makes Y Z):
  ... manheisst (NP-OB1 (D^A^PL die)) (NP-SMC (FW^A^PL Alkatrases)).
... da er (NP-OB1 (PRO^A^SG yn)) (NP-SMC (N^A^SG Ritter)) machen solt.
  
• NP-SMC may also be the secondary predicate of a subject:
  ... (NP-SBJ (NPR Adam)) geschaffen was (NP-SMC (ONE eyn) (ADJ vrisscher) (N man))
  (Note that we follow CHLG in doing away with IP-SMC for such structures, so the small clause is not represented as a constituent.)

• NP-POS is for a range of (usually genitive) NP types in addition to posessives, including partitives (including complements of NUM or Q):
  (NP-OB1 (NUM^A^PL zwen) (NP-POS (ADJ^G^PL krefftiger) (N^G^PL schlege))),
  and complements of N: (NP (N^A^SG forcht) (NP-POS (D^G^SG des) (N^G^SG tods))).
  
• NP-POS may also occasionally be used when a (non-genitive) possessive pronoun requires a phrase, such as seine in this example: 
  (NP-SBJ (NP-POS (NP-POS (PRO$ seine) (CONJP (CONJ und) (NP-POS (PRO$ seiner) (N Schwester)))) (N Kinder)) 'his and his sister's children'
  
• Use NP-POS as the sole constituent of another NP only in clear instances of elision head:
  und (NP-SBJ (NP-POS (D des) (ADJ gleichs))) 'and [things] similar to that'

• NP-COM is the complement (usually genitive or dative) of an adjective or adverb: 
  (NP-SBJ (PRO^N^SG er))  (ADJP-PRD (NP-COM (D^G^SG dessen)) (ADJ wirdig))  (BEPI ist)
  See treatment of phrases for a list of adjectives that have complements, versus free datives. (Unlike in some other Penn corpora, we use NP-POS for complements of N.)
• NP-MSR is the measure phrase modifier of a N, ADJ, ADV, or PP:
  (ADJP (NP-MSR (NUM^A^PL zwentzig) (N^A^PL schuoch))(ADJ weit))
(ADJP-PRD (NP-MSR (INDPRO nichts)) (ADJ wert))
  Treat a non-genitive N quantified by a measure phrase as the head of the nominal (unlike eyne summe gelds which would have summe as the head and gelds in an NP-POS):
  (NP-OB1 (NP-MSR (ONE eyne) (N some)) (N gelt))
(Durations of time are NP-TMP, not NP-MSR, unless they modify another phrase.)
• NP-PRN is a parenthetical or appositive NP. If NP-PRN is adjacent to the N that it modifies, they are sisters and NP-PRN does not need a grammatical function tag. If non-adjacent, NP-PRN receives a grammatical function tag so that its antecedent can be identified:

Our annotation of temporal phrases differs from the Penn corpora of English in two ways. First, all bare, clausal temporal NPs are tagged NP-TMP. Secondly, we use a flat structure for longer time expressions only if there are no German function words that indicate a more refined structure.

When to use flat structure:

• When there are no (German) function words, or when the function words don't distinguish the parts of the time expression: (NP-TMP (D^A^SG den) (NUM^A^SG 01.12.1900))
• When the whole time expression is in a foreign language: (NP-TMP (FW Anno) (FW domini) (NUM^A^SG 1447) (ADJ^G^SG S.) (NPR^G^SG Ceciliae))

Use articulated, syntactic structure when there are German articles or prepositions:

Note that if the word 'year' and a numerical year are present, the latter is in apposition to the former:

(PP (P i@) (NP (D @m) (N jar) (NP-PRN (NUM 1549))))

Following a date that is a cardinal number, assume that a month is genitive: 
(NP-TMP (D den) (ADJ ersten) (NP-POS (NPR^G^SG Dezember)) )('the first (day) of Dec.', not 'the first Dec.')

Syntactically structured time phrases are generally sisters:

(NP-TMP (D den) (ADJ ersten) (NP-POS (NPR^G^SG Dez.)) )   (NP-TMP (NUM^A^SG 1900))

Unless very clear that one phrase modifies another, e.g. when vor or nach further specify the day:

(PP (P an) (NP (NPR Mitchwuchen) (PP (P vor) (NP (NPR Cecilee)))))

Function words may cause a shift from flat to articulated structure:

Here, 'on S. Martin's night' is sister to 'AD 1448' because there is clearly a PP but neither is part of the other: (NP-TMP (FW Anno) (FW domini) (FW m.cccc.x.lviii)) (PP (P uff) (NP-POS sant martinis) (N nacht)))

Choice of case:

• NUM^A^SG for any parts of dates or times that are otherwise unmarked for case (see Anno domini 1447 S. Ceciliae above).
• NPR^G^SG for Saint's days even if not in an NP-POS (as with S. Cecliae above).

Determinining head vs. modifier:

If the day/year that is specific point in time, it is the 'head' of the time phrase:

(PP (P a@) (NP (D @m) (ADJ 14.) (N Tag) (PP nach Ostern) )) 'on the 14th day after Easter'

(NP-TMP (PP nach Christi geburt) (NUM^A^SG 1078)) 'A.D. 1078' (not '1078 [years] after Christ's birth')

However, if the days/years (in plural) are a measurement w.r.t. a specific point in time, the specific point in time is the head:

(PP (NP-MSR 14 tage) (P nach) (NP (NPR ostern))) '[the day] 14 days after Easter' (annotating as NP-TMP would imply a duration of 14 days beginning at Easter)

(PP (P nach (NP (NP-POS Christi (N geburt)) (NP-MSR (NUM^A^PL 1078) (N^A^PL Jahre))) '[the year] 1078 years after Christ's birth', not a duration of 1078 years.

• NP-DIR and NP-LOC are occasionally used for bare NP adjuncts that express direction or location:
    wir setzten vnser Coß (NP-DIR (N^A^SG Seud) (N^A^SG SeudWest))
  
• NP-ADT is reserved for adjuncts (especially genitive, corresponding to a PP in modern English or German) that cannot be classified as NP-TMP, -DIR, or -LOC:
  (NP-ADT (PRO$^G^SG deiner) (N^G^SG rede))  (BEPI bin)  (NP-SBJ (PRO^N^SG ich))  (ADJP-PRD (ADV fast) (ADJ vnmuotig)) 'Because of your speech I am almost unnerved.'