The Community Tequiyotl
It is one expression of the reciprocal relationship of the Cenyeliztli (family) with their community i.e. the Calpolli.
TEQUIYOTL: work, labor, payment of labor, contribution.
COATL: 1. snake, serpent, culebra, serpiente
2. twin, cuates, gemelo
3. duplicity, reciprocity, complementarity
In the expression COATEQUIYOTL, the COA carries the sense of two entities sharing a single complimentary relationship.
For example, NOTZA means "to call or summon someone", but COANOTZA means "to invite someone" i.e. to enter into a Host-and-Guest relationship. A person cannot be a host without a guest, and vica versa.
COATEQUIYOTL carries the sense of TEQUIYOTL that is performed in a mutual beneficial Give-and-Take relationship within the community.
Traditionally the Coatequiyotl consisted of communal projects that were done for the benefit of the Calpolli, such as planting and harvesting of crops, road maintenance, irrigation projects, building and maintaining Calpolli structures, and similar efforts. On a larger scale the Altepetl (agropolis) would require that each Calpolli to contribute to larger projects that for the benefit of the many Calpolli in the Altepetl.