Font Embedding Bits: fsType Explained

fsType Permission Levels

The gap between fsType's intent and its actual enforcement reflects the broader challenge of digital rights management for fonts. In the early 2000s, major desktop publishing applications—Adobe InDesign, QuarkXPress, and Microsoft Word—did honor fsType restrictions, checking the bit before embedding fonts in exported PDFs or documents. This created a practical compliance layer for the era's primary use case: document embedding. Web browsers, however, were never designed as DRM enforcement tools. The web's open architecture treats font files as stylistic resources loaded over HTTP, and implementing fsType enforcement would break legitimate usage patterns while being trivially circumvented by anyone motivated to do so.

Open-source fonts released under licenses like the SIL Open Font License or Apache 2.0 uniformly set fsType to 0x0000, correctly reflecting their permissive license terms in the bit field. Proprietary commercial fonts may set any value, but the bit does not reliably predict web licensing availability. A font with fsType 0x0004 (Preview and Print) from a major foundry may have a separate web font license available for purchase; a font with fsType 0x0000 from an obscure source may still restrict web use through its EULA. Foundries that operate web font services—like Adobe Fonts and Fontspring—typically modify fsType to 0x0000 in their hosted versions, since those versions are contractually covered by the subscription license regardless of the original bits.

fsType and Web Fonts

Web browsers completely ignore fsType when loading web fonts via @font-face. There is no technical barrier—a font with fsType 0x0002 (Restricted) will load and render in browsers just like any other font.

How to Check fsType

# Using fontTools (Python)
from fontTools.ttLib import TTFont
font = TTFont('myfont.ttf')
print(f"fsType: {font['OS/2'].fsType}")

# Using ttx to dump OS/2 table
ttx -t OS/2 myfont.ttf
# Then check the generated .ttx file for fsType

# Online tools
- Wakamai Fondue (wakamaifondue.com)
- FontDrop (fontdrop.info)
- Font Squirrel's Font Analyzer

# FontForge
Element → Font Info → OS/2 → Misc → fsType

# Python: decode any fsType value
def decode_fstype(value):
    results = []

    # Embedding type (bits 0-3)
    embed_bits = value & 0x000F
    if embed_bits == 0x0000:
        results.append("Installable Embedding (no restrictions)")
    elif embed_bits & 0x0002:
        results.append("Restricted License Embedding")
    elif embed_bits & 0x0004:
        results.append("Preview & Print Embedding")
    elif embed_bits & 0x0008:
        results.append("Editable Embedding")

    # Additional restrictions (bits 8-9)
    if value & 0x0100:
        results.append("No Subsetting Allowed")
    if value & 0x0200:
        results.append("Bitmap Embedding Only")

    return results

# Examples:
decode_fstype(0x0000)  # ['Installable Embedding (no restrictions)']
decode_fstype(0x0104)  # ['Preview & Print Embedding', 'No Subsetting Allowed']
decode_fstype(0x020A)  # ['Editable Embedding', 'Bitmap Embedding Only']

Building font delivery infrastructure benefits from programmatic fsType auditing. The fontTools Python library provides direct access to the OS/2 table: TTFont('font.ttf')['OS/2'].fsType returns the integer value, which you can then decode using the bit masks above. Automated pipelines can flag fonts with fsType 0x0002 (Restricted) before they enter a web delivery system, prompting a license review before deployment. Open-source font collections like Google Fonts have performed this audit at scale, normalizing fsType to 0x0000 for all hosted fonts to reflect the permissive web license granted by the service, regardless of what the original binary contained.

The interaction between fsType and font subsetting deserves separate attention. The No Subsetting bit (0x0100) signals that the font must be embedded complete, without removing any glyphs. In a web font context where subsetting is a standard and significant optimization—reducing file sizes by 80–95% for Latin-only deployments—this bit creates a practical conflict. A font with 0x0100 combined with any embedding permission bit technically permits embedding but prohibits the character-set reduction that makes web delivery practical. In practice, web font licenses negotiated directly with foundries typically address subsetting rights explicitly in their terms, making the bit-level restriction secondary to contractual permission. When licensing fonts for web use, verifying subsetting rights in the actual license agreement is more reliable than reading the fsType bit.

Related Technical Guides