FLM Features

FLM organizes its functionality into features — pluggable modules that define macros, environments, and specials. Features are the mechanism by which FLM provides (and lets you customize) the available markup.

FLM is a framework, not a fixed language. The macros and environments available in your documents depend entirely on which features are loaded. You can enable or disable any feature, configure its behavior, or write your own custom features.

How Features Work

Each feature is a Python class inheriting from Feature. A feature:

• Defines macros, environments, and/or specials via its add_latex_context_definitions() method.

• May provide a DocumentManager for per-document state (e.g., managing numbering or collecting footnotes).

• May provide a RenderManager for per-render state.

• Can declare dependencies on other features.

Default Features

The following features are enabled by default when using the flm command-line tool (via the built-in default_config.yaml).

Note

When using the Python API with standard_features(), some of these features (notably theorems) default to disabled and must be explicitly enabled. The command-line tool’s default configuration enables a broader set of features than the standard_features() helper.

Feature	Description	Syntax Reference
baseformatting	Text emphasis, bold, character escapes, paragraph breaks, non-breaking spaces.	Text Formatting
href	Hyperlinks: \href, \url, \email.	Hyperlinks
verbatim	Verbatim and code typesetting: \verbcode, \verbtext, verbatimcode, verbatimtext environments.	Verbatim and Code
math	Mathematics: inline \( ... \), display environments (equation, align, gather), \eqref.	Mathematics
headings	Sectioning commands: \section, \subsection, etc.	Headings
enumeration	Lists: enumerate, itemize, description environments.	Lists
refs	Cross-reference management: \ref, \hyperref.	Cross-References
endnotes	Endnotes and footnotes: \footnote.	Footnotes
floats	Figures and tables: figure, table environments with captions and numbering.	Figures and Graphics
graphics	Graphics inclusion: \includegraphics.	Figures and Graphics
defterm	Definition terms: defterm environment, \term macro.	Definition Terms
theorems	Theorems, lemmas, proofs, and related environments.	Theorems and Proofs

Opt-In Features

The following features are available but must be explicitly enabled in the configuration:

Feature	Description	Syntax Reference
substmacros	Custom substitution macros defined via configuration.	Substitution Macros
quote	Block quote environments with attribution.	Block Quotes
cells	Table-like cell layout.	Tables and Cells
citations	Citations (via the flm-citations extension package).	Citations
annotations	Inline annotations and comments.	See flm.feature.annotations
markup	Custom text formatting macros and semantic block environments.	See flm.feature.markup

Enabling and Configuring Features

Features are configured in your flmconfig.yaml or in the document’s YAML front matter. See Feature Configuration for the full details.

Enable a feature with default options:

flm:
  features:
    quote: {}

Disable a feature:

flm:
  features:
    theorems: false

Configure a feature with custom options:

flm:
  features:
    endnotes:
      categories:
        - category_name: footnote
          counter_formatter: roman
          heading_title: 'Footnotes'
          endnote_command: 'footnote'

Using Features from Extension Packages

External features can be loaded by using their fully qualified Python module path as the feature name in the configuration:

flm:
  features:
    'my_extension_package.my_feature': {}

Or by importing the package’s default configuration with $import:

$import:
  - pkg:my_extension_package

Writing Custom Features

You can write your own features by creating a Python class that inherits from Feature. The key method to implement is add_latex_context_definitions(), which returns a dictionary of macros, environments, and specials to register.

See the FLM “Features” - Extensions API documentation and the source code of the built-in features in the flm/feature/ directory for examples.