<\body> The contains high-level markup which can be used by the user to define new numbered environments for theorems, remarks, exercises and figures: <\explain|> This meta-macro is used for defining new theorem-like environments. The first argument specifies the name for the environment (like ``experiment'') and the corresponding text (like ``Experiment''). When defining a new theorem-like environment like , an unnumbered variant is automatically defined as well. <\explain|> Similar as , but for remarks. <\explain|> Similar as , but for exercises. <\explain|> Similar as , but for figures. When defining a new type of figure, like ``picture'', the macro defines both the inline environment and the block-environment , as well as the unnumbered variants and . The theorem-like and remark-like environments belong to a common counter-group . By default, we use American-style numbering (one common counter for all environments). When selecting the package , each environment uses its own counter. All exercises and figures use their own counter-group. More generally, the counter-group regroups the counters for all standard environments. Typically, all counters in this group are prefixed in a similar way (for instance by the number of the chapter). Figure shows how the hierarchical organization of this counter group. <\big-figure|||>>|>>|>>|>>>>>>>||>>|>>>>>>||>>|>>>>>>||>> Organization of the counters for the standard environments. In addition to the standard theorem-like, remark-like, exercise-like and figure-like environments, other numbered textual environments may be defined using the macro. These environments may be based on arbitrary counter-groups: <\explain|> The first argument is the name of the counter to which the new environment belongs. The second argument is the name of a binary macro for rendering the environment. The arguments of the rendering macro are a name (like ``Theorem 3.14'') and its body. The remaining arguments are similar as for . For instance, in the standard style-sheets, is defined by <\tm-fragment> <\inactive*> ||theorem-env|render-theorem>>> We recall that you may add new counters or counter-groups to the counter-group using the and macros, as described in the section about counters. <\initial> <\collection>