This is an announcement for the paper "Haar type and Carleson constants" by Stefan Geiss and Paul F. X. Mueller. Abstract: We determine the sub-collections of the dyadic intervals that are able to detect the Haar type of a Banach space. The underlying dichotomy is expressed in terms of the Carleson packing condition. Archive classification: math.FA Mathematics Subject Classification: 46B07 ; 46B20 Citation: Bull. Lond. Math. Soc. 40 (2008) 432-438 The source file(s), paper_revised050108.tex: 20601 bytes, is(are) stored in gzipped form as 0902.1955.gz with size 7kb. The corresponding postcript file has gzipped size 74kb. Submitted from: pfxm@bayou.uni-linz.ac.at The paper may be downloaded from the archive by web browser from URL http://front.math.ucdavis.edu/0902.1955 or http://arXiv.org/abs/0902.1955 or by email in unzipped form by transmitting an empty message with subject line uget 0902.1955 or in gzipped form by using subject line get 0902.1955 to: math@arXiv.org.