Clarify usage of \problemname

Author: niemela

spec/2023-07-draft.md

@@ -439,7 +439,10 @@ It is the judging system's responsibility to wrap this text in an appropriate La
 The LaTeX class shall provide the convenience environments `Input`, `Output`, and `Interaction` for delineating sections of the problem statement.
 It shall also provide the following commands:
 
-- `\problemname`, which must be the first line of the problem statement and places the `name` value matching the problem statement's language from `problem.yaml` into the problem statement header.
+- `\problemname{name}`, which should typically be the first line of the problem statement and places the problem name into the problem statement header.
+  The argument `name` is optional.
+  If it is missing, the `name` value from `problem.yaml` matching the problem statement's language is used.
+  If it is present, it is used instead, and must be a LaTeX-formatted version of the `name` value from `problem.yaml` matching the problem statement's language.
   In some cases, the problem name might contain math formulas or other text that should be typeset specially.
   In this case, the `\problemname{name}` command should be used instead and overrides the name in the header with `name`, a LaTeX-formatted version of the problem name.
 - `\illustration{width}{filename}{caption}`, a convenience command for adding a figure to the problem statement.