RRGparbank

To change a label, click on a node to select a different label from a list. The syntactic category and the function tag (before and after the dash "-") must be selected separately by clicking on the corresponding part of the label.
To add a function tag to a node that does not have one yet, drag it from the list of function tags onto the node.
Re-attach a node by dragging and dropping it on a new parent. This can be used to created discontinuous constituents.
Similarly, nodes can be removed and new ones added by dragging to/from below the tree.
Finally, the bracketing can be edited manually in the text box below the tree; press "validate" to update the tree. Whitespace is ignored. Each token must have a dedicated POS tag.

				[...wait for it...]

(SENTENCE
  (CLAUSE
    (CORE
      (NP (OP-DEF 0=His) (CORE_N (NUC_N (N 1=questioners))))
      (ADVP-PERI (CORE_ADV (NUC_ADV (ADV 2=now))))
      (NUC
        (AUX-TNS 3=were)
        (NP
          (NP
            (CORE_N
              (OP-NEG 4=not)
              (NUC_N (N 5=ruffians))
              (PP-PERI
                (CORE_P
                  (NUC_P (P 6=in))
                  (NP
                    (CORE_N
                      (AP-PERI (CORE_A (NUC_A (A 7=black))))
                      (NUC_N (N 8=uniforms))))))))
          (NP
            (CLM 9=but)
            (CORE_N (NUC_N (N-PROP 10=Party) (N 11=intellectuals)))
            (NP-PERI
              (, 12=,)
              (CORE_N
                (AP-PERI (CORE_A (NUC_A (A 13=little))))
                (AP-PERI (CORE_A (NUC_A (A 14=rotund))))
                (NUC_N (N 15=men))
                (PP-PERI
                  (CORE_P
                    (NUC_P (P 16=with))
                    (NP
                      (NP
                        (CORE_N
                          (AP-PERI (CORE_A (NUC_A (A 17=quick))))
                          (NUC_N (N 18=movements))))
                      (NP
                        (CLM 19=and)
                        (CORE_N
                          (AP-PERI (CORE_A (NUC_A (V-GER 20=flashing))))
                          (NUC_N (N 21=spectacles)))))))))
            (SENTENCE-PERI
              (, 22=,)
              (CLAUSE
                (PrCS (NP-REL (PRO-REL 23=who)))
                (CORE
                  (NUC (V 24=worked))
                  (PP (CORE_P (NUC_P (P 25=on)) (NP (PRO 26=him))))
                  (PP-PERI
                    (CORE_P
                      (NUC_P (P 27=in))
                      (NP
                        (CORE_N
                          (NUC_N (N 28=relays))
                          (PP-PERI
                            (CORE_P
                              (NUC_P (P 29=over))
                              (NP
                                (CORE_N
                                  (NUC_N
                                    (N 30=periods)
                                    (CLAUSE-PERI
                                      (PrCS (NP-REL (PRO-REL 31=which)))
                                      (CORE
                                        (NUC (V 32=lasted))
                                        (NP
                                          (CORE_N
                                            (QP
                                              (CORE_Q
                                                (NUC_Q
                                                  (NUC_Q (QNT 43=ten))
                                                  (NUC_Q
                                                    (CLM 44=or)
                                                    (QNT 45=twelve)))))
                                            (NUC_N (N 46=hours))
                                            (PP-PERI
                                              (CORE_P
                                                (NUC_P (P 47=at))
                                                (NP
                                                  (OP-DEF 48=a)
                                                  (CORE_N
                                                    (NUC_N (N 49=stretch)))))))))
                                      (SENTENCE-PERI
                                        (. 33=-)
                                        (CLAUSE
                                          (CORE
                                            (NP (PRO 34=he))
                                            (NUC (V 35=thought)))
                                          (, 36=,))
                                        (CLAUSE
                                          (CORE
                                            (NP (PRO 37=he))
                                            (OP-MOD 38=could)
                                            (OP-NEG 39=not)
                                            (NUC (AUX 40=be) (A 41=sure))))
                                        (. 42=-))))))))))))))))))))
  (. 50=.))