Proclaim

In Plain-TeX there is the command \proclaim which is very handy when writing mathematics and stating Theorems, Lemmas, Definitions and so on. Unfortunately it doesn't allow one to number automatically these statements in order to refer to them through cross referencing, and somehow it has disappeared from ConTeXt.

If one wishes to number in a sequential way all these « proclaims », here is a solution, which works veru well in ConTeXt mkii (for a solution with mkiv see below):

%% defining an enumeration environment replacing Plain-TeX's \proclaim
%
\defineenumeration[proclaim]
	[text=,
	style=slanted,
	title=yes,
	titleleft=,
	titleright=,
	location=serried,
	width=fit,
	right={. }]
\setupnumber[proclaim][way=bysection,numbersection=yes] %% this can be changed according to one's wishes
%
%% end definition \proclaim

After having defined this, one can use it in the following way:

\starttext
\title{On proclamations}
\blank
When there is not a declared section, the numbers have no prefix as in the following:

\startproclaim[def:test]{Definition}
This is a definition.
\stopproclaim

\startproclaim{Lemma}
This is a lemma.
\stopproclaim

\section{Here is a section}

When there is a declared section, the numbers have as prefix the section number, as in the following:

\startproclaim{Lemma}
Here is another lemma.
\stopproclaim

\startproclaim[thm:result]{Theorem}
This is our main theorem.
\stopproclaim

\section{Here is another section}

When there is a declared section the numbers have as prefix the section number, as in the following:

\startproclaim[lem:resultB]{Lemma}
Here is an elementary lemma.
\stopproclaim

\startproclaim{Corollary}
This is a corollary.
\stopproclaim

Note that we can refer to our results in the following way: according to the definition \in[def:test] we see that theorem \in[thm:result] is
 an easy consequence  of  lemma \in[lem:resultB].

\stoptext

and we get this upon typesetting in mkii:

In mkiv there is another solution which consists in defining first a certain « enumeration » (in the example below for Remarks) and then use the counter created for this enumeration in other enumerations such as Lemmas, Theorems, etc.

%% Defining \proclaim style Remark, Lemmas, Theorem, Corollary, etc
\defineenumeration[remark]
	[text=Remark,
	location=serried,
	width=fit,
	right={.~}]
\setupenumerations[remark]
	[prefix=yes,
	prefixsegments=section] % or prefixsegments=chapter:section
\setupnumber[remark][way=bysection]

\defineenumeration[lemma]
	[text=Lemma,
	location=serried,
	width=fit,
	counter=remark, % only use counter of remark
	style=slanted,
	right={.~}]
\setupenumerations[lemma]
	[prefix=yes,
	prefixsegments=section]

\defineenumeration[theorem]
	[text=Theorem,
	location=serried,
	width=fit,
	counter=remark,
	style=slanted,
	right={.~}]
\setupenumerations[theorem]
	[prefix=yes,
	prefixsegments=section]

\starttext

\title{First and only title of the article}

Here we don't have any section.

\startremark
This is a silly remark.
\stopremark

\startlemma[lem:elem]
This is an elementary result.
\stoplemma

\starttheorem
This is a deep theorem.
\stoptheorem

\startremark
This is a silly remark.
\stopremark

\startlemma
This is an elementary result.
\stoplemma

\starttheorem
This is a deep theorem.
\stoptheorem

\section{This is a section}

Here we do have a section.

\startremark
This is a silly remark.
\stopremark

\startlemma
This is an elementary result.
\stoplemma

\starttheorem
This is a deep theorem.
\stoptheorem

\startremark[rem:silly]
This is a silly remark.
\stopremark

\startlemma
This is an elementary result.
\stoplemma

\starttheorem[thm:deep]
This is a deep theorem.
\stoptheorem

As mentioned in remark \in[rem:silly], the results of lemma \in[lem:elem] and that of theorem \in[thm:deep] are trivial.

\stoptext

This results in the following: