[NTG-context] Letters in the first level head instead of numbers

Hello, maybe already questioned in the past, but I cannot find the answer: How to change the numbering style for a particular head (e.g. section) from numbers (1, 2...) to letters (A, B...) - which option and value (http://wiki.contextgarden.net/Reference/en/setuphead)? Thank you in advance. Kind regards, Lukas -- Ing. Lukáš Procházka [mailto:LPr@pontex.cz] Pontex s. r. o. [mailto:pontex@pontex.cz] [http://www.pontex.cz] Bezová 1658 147 14 Praha 4 Tel: +420 244 062 238 Fax: +420 244 461 038