  The main aim of this work is to relate integrability in QFT with a complete
particle interpretation directly to the principle of causal localization,
circumventing the standard method of finding sufficiently many conservation
laws. Its precise conceptual-mathematical formulation as "modular localization"
within the setting of local operator algebras also suggests novel ways of
looking at general (non-integrable) QFTs which are not based on quantizing
classical field theories. Conformal QFT, which is known to admit no particle
interpretation, suggest the presence of a "partial" integrability, referred to
as "conformal integrability". This manifest itself in a "braid-permutation"
group structure which contains in particular informations about the anomalous
dimensional spectrum. For chiral conformal models this reduces to the braid
group as it is represented in Hecke- or Birman-Wenzl- algebras associated to
chiral models. Another application of modular localization mentioned in this
work is an alternative to the BRST formulation of gauge theories in terms of
stringlike vectorpotentials within a Hilbert space setting.
