Revisiting The Role Of Two-Letter Font Commands In Modern Latex

Specifying Fonts in LaTeX

LaTeX provides a powerful system for specifying fonts in a document. At the core of this system are font command shortcuts that allow the user to quickly switch between common fonts. The most basic of these commands are two-letter codes that switch the font family and series - \rm for roman (serif), \sf for sans-serif, and \tt for monospaced (typewriter). These commands originated in early versions of LaTeX as a convenience for specifying sections of text with different fonts.

While modern LaTeX has introduced more advanced font selection methods, the two-letter font commands still serve an important role due to their simplicity and backwards compatibility. This article explores the usage and effects of these font commands, analyzes their role in modern documents, and provides recommendations for deciding when they are appropriate to use.

Usage and effects of font commands

Example code showing font changes

The basic syntax for the two-letter font commands is straightforward - the command is inserted before the text that should use the different font:

\rm Roman font text
\sf Sans-serif font text 
\tt Monospaced font text

The font change persists until another font command is used or the end of the group (usually the environment) in which it appears. For example:

```latex
{\sf This paragraph uses a sans-serif font family}\\

\rm This one returns to the default roman font
```

Font attributes like bold or italic can be layered on top by using the \bf or \it commands:

```latex
\bf \sf Bold sans-serif text\\
\rm \it Italic roman text
```

Visual demonstration of font changes

When these font commands are compiled, the visual result is a shift in fonts:

The roman text appears in a classic serif font with transitional thickness and brackets on stems. The sans-serif text appears more uniform and clean without serifs. Finally, the monospaced font appears mechanical and aligned, like text from a typewriter.

This demonstrates the power of the two-letter font commands to quickly modify the appearance of text elements in a LaTeX document with only a couple keystrokes.

Recommendations for modern LaTeX documents

Built-in fonts vs. imported fonts

When using fonts in a LaTeX document, the main decision is whether to use built-in fonts or imported font packages:

• Built-in fonts: LaTeX has a set of fonts predefined in its system, including roman, sans-serif, and monospaced families. These built-in fonts provide basic font needs but limited flexibility in style.
• Imported fonts: Packages like fontspec allow you to import external font files to access thousands of font families. However, this requires properly installed fonts and configuration.

For most purposes, the built-in LaTeX fonts are sufficient, especially for print media. These fonts are designed to be clean, legible, and appropriate for academic writing. Unless a specific font style is needed, built-in fonts may be preferrable.

Font consistency for improved readability

When multiple fonts are used in a document, it is important to employ them thoughtfully with consistency and clarity in mind. Just because LaTeX makes it easy to quickly change fonts does not always mean you should do so liberally.

Frequent unmotivated font shifts can give documents a disjointed and unprofessional feeling. On the other hand, a few deliberate font changes at structural boundaries can help guide the reader and establish hierarchy within sections.

For the best readability, limit font variations to certain situations like headings, code blocks, or emphasis. Keep sections of body text and prose in a single consistent roman font without overly-frequent style shifts.

When to use two-letter font commands

Given the power but potential drawbacks of frequent font changes, when should authors actually employ these two-letter LaTeX font commands versus other font specification methods?

Backwards compatibility with old documents

For editing older LaTeX documents, the \rm, \sf, and \tt commands remain useful for quick font changes. Since many legacy documents rely heavily on these macros for styling text, the two-letter shortcuts preserve rendering when working with these files.

Font changes mid-document

The other main use case for the classic font commands is to change text appearance dynamically within a document's body text outside of semantic logical structures like headings or code blocks. While used sparingly, a \sf or \tt font break can emphasize key terms or transitions between ideas.

Conclusion

In summary, while LaTeX offers many powerful tools for typography, the classic two-letter font commands still serve a role due to their ubiquity, backward compatibility, and ease of use for text styling. Modern best practices recommend consistent, motivated use of different fonts rather than haphazard styling changes. For most documents, built-in fonts only need light decoration with commands like \em rather than intensive manipulation. With mindful usage, both new and classic LaTeX font tools can create clean, professional documents.