404. The fallback original term: a plain English rendering for when the term will not travel¶

Some English terms carry their meaning in a metaphor that other languages do not share. Overshoot names, in a font editor, the few units by which an o rises above the x-height so that it looks as tall as an x; the word itself says only that something went past a line. Stem is a word from plants. Advance says that something moved forward, not how far a glyph box is. A translator who meets such a term has three bad options: borrow the English word, which a reader may not know; translate the metaphor literally, which produces a calque nobody uses; or explain the concept, which produces a phrase too long for a label.

The fallback original term is a fourth option. Beside the English term, the glossary stores a short, plain English rendering of the same concept, chosen so that translating it literally gives a defensible target term. The translator can translate that instead. This chapter explains what a fallback is and what it is not, when to write one, how a translator uses it and where it lives in the data.

The case that produced the idea¶

The Polish FontLab interface first rendered overshoot as wydłużenie optyczne, "optical lengthening". The phrase is accurate and describes the effect, but it is long, it says lengthening where the shape also extends downward below the baseline, and it gives no adjective or compound to build on. In issue 146 the founder replaced it with naddatek, the ordinary Polish word for an allowance or surplus, glossed in the same line as an optical surplus, and added: "we should also use this principle in other languages if we're unsure".

That remark names the principle. What the founder translated was not overshoot but a plainer English description of the concept, optical surplus, keeping only the noun; in a font editor the optical context goes without saying. The Polish core memory records the decision with the note naddatek optyczny; ta zasada może służyć także innym językom: the principle may serve other languages too. The English glossary now stores optical surplus as the fallback of overshoot, so that the next translator into any language starts where the founder finished. (Issue 147 phrased the same example as architectural surplus; the glossary kept the wording of issue 146.)

Stem followed the same path. Its glossary definition calls a stem the main stroke of a letter, and its fallback is main stroke. After an evidence review of Polish type literature, the Polish interface used kreska główna, which is exactly the literal translation of that fallback, until the founder settled on trzon, the shaft or trunk, which yields the compounds the interface needs: trzon standardowy for standard stem, łącze trzonu for stem link. The interim term shows what a fallback is for: it gives a language a correct, understandable term until a better one is chosen.

What a fallback is, and what it is not¶

A fallback is a second source text for one concept. It is not a synonym to vary prose with, and it is not a definition.

	Fallback original term	Definition	Synonym (`also`)
Length	At most six words	Up to 100 words	One term
Form	A noun phrase or verb phrase, like the term	Full sentences	A variant spelling or alternative name
Purpose	To be translated literally when the term will not travel	To explain the concept for checking	To be recognized and mapped back to the term
Appears in the English product	No	In glossary pages and help	Sometimes, as a variant

The test for a good fallback is the literal translation. Translate it word for word into a few languages. If the result is a plausible term in each, one a professional would accept in a label, the fallback works. If the result is an explanation, the fallback is a definition in disguise and should be shortened. Optical surplus passes: naddatek optyczny, optischer Überschuss, excedente óptico. The extra height a round letter needs to look aligned fails: it is a definition.

A fallback also avoids the source of the difficulty. Main stroke removes the botany from stem. Glyph box width, the fallback of advance width, removes the typewriter. Layout subroutine, the fallback of lookup, removes the programmer's jargon and says what the thing is in an OpenType font.

When to write one, and when not to¶

Write a fallback when all three conditions hold:

The term is translatable. It names a concept, not a brand.
The English word depends on a metaphor, an etymology or a jargon habit that a target language may not share. A term the professions share, such as kerning, may still carry one for the many languages that lack the loan; the FontLab glossary errs on that side, which is why most of its entries have a fallback.
A plain rendering exists that is short enough to be a term and precise enough to name only this concept.

Do not write one for brands, trademarks, product names or file format identifiers. They are not translated, so a second source text makes no sense; the FontLab checker refuses a fallback on any term that is marked non-translatable or belongs to the brand category. FontLab, FontAudit and Vexy have none.

Do not write one that repeats the term. The checker refuses that too, along with any fallback of more than six words or containing a dash.

Do write one for coined feature names when they are translatable. The FontLab glossary gives Sketchboard the fallback scratch canvas, Matchmaker the fallback master matcher, Power Guide linked guideline, Genius node self-balancing node. These tell a translator what the name refers to in the most direct words available, which is what a translator needs before deciding whether to translate the name playfully (chapter 407).

How a translator uses it¶

The fallback does not replace research. It is what a translator reaches for when research comes up empty or produces something unusable.

Look for an attested equivalent first (chapter 406). German type designers say Dickte for advance width and Überstand for overshoot; French says fût for stem. Where the profession has a word, use it, and the fallback plays no part.
If there is none, or only a calque or an explanatory phrase, translate the fallback literally and treat the result as a candidate term.
Test the candidate. Does it name the concept and nothing else? Does it fit the tightest label that uses it? Can the language derive the forms it needs: the plural, the adjective, the compound (chapter 408)?
Shorten where context allows. Naddatek optyczny became naddatek, because in a font editor the optics go without saying.
Record the result in the core memory with a note saying that it came from the fallback, so a reviewer can see the route.

The Polish FontLab terms of issue 146 show how often the literal route works. Several read as direct translations of the fallback:

English term	Fallback	Polish	Literal sense of the Polish
overshoot	optical surplus	naddatek	surplus, allowance
advance width	glyph box width	szerokość pola	width of the field
vertical advance	glyph box height	wysokość pola	height of the field
lookup	layout subroutine	podprogram zecerski	typesetter's subroutine
stem (interim)	main stroke	kreska główna	main stroke

Not every Polish decision follows the fallback, and it does not have to. Nudge has the fallback push move, and an earlier Polish rendering, pchnięcie, was close to it. The founder chose holowanie, towing, which is funnier and gives superholowanie for Power Nudge. The fallback is a floor, not a ceiling: it guarantees a correct term, and a better idea may still win.

Where the fallback lives¶

The fallback is English data, so it lives with the English term. In the glossary it is an optional field:

id: stem
term: stem
category: type-design
status: approved
definition: |
  A stem is a main stroke of a letter, usually the vertical one: ...
fallback: main stroke
translatable: true

Every core memory copies it as a property of the translation unit, beside the term id and status, so that a tool that reads only the memory still sees it:

<tu tuid="term:overshoot">
 <prop type="x-term-id">overshoot</prop>
 <prop type="x-category">type-design</prop>
 <prop type="x-translatable">yes</prop>
 <prop type="x-fallback">optical surplus</prop>
 <prop type="x-status">approved</prop>
 <note>Overshoot is the extension of a rounded or pointed shape ...</note>
 <tuv xml:lang="en"><seg>overshoot</seg></tuv>
 <tuv xml:lang="pl">
  <note>Naddatek optyczny; ta zasada może służyć także innym językom.</note>
  <seg>naddatek</seg>
 </tuv>
</tu>

TMX 1.4 reserves the x- prefix for user-defined property types, so the file stays valid for any tool that reads TMX (chapter 306). The styleguide's coretm.py writes the property from the glossary, and check_terms.py fails when a memory's x-fallback disagrees with the glossary's fallback, so the two cannot drift apart.

A translation pipeline can use the property too. When a target language has no approved rendering of a term, the batch sent to an engine can carry the fallback beside the English term, with an instruction to translate the fallback as a term. Whether a pipeline does this is a design decision for the glossary enforcement step described in chapter 605; the data is there either way.

Traps¶

Definition creep. A fallback that grows into a clause has become a definition. Keep it at six words or fewer, and prefer two or three.
Jargon for jargon. Pair spacing correction for kerning helps; GPOS adjustment would not. The fallback must be plainer than the term.
Leaking into English. The fallback is not an alternative for English writers. The English interface and manual keep the term; the fallback exists for translators.
Mistaking it for approval. A literal translation of a fallback is a candidate. It still needs a reviewer, a status and, if it is chosen, a ledger entry.

Sources¶

issues/146.md and issues/147.md in the fl10n repository
glossary/schema.md, glossary/terms/overshoot.yaml, glossary/terms/stem.yaml, scripts/check_terms.py, scripts/coretm.py and localization/tm/pl-core.tmx in the vexy-fontlab-writing-styleguide repository
localization/pl and localization/de in the vexy-fontlab-writing-styleguide repository
data-fontlab-cpp/i18n/review/2026-09-29-issue-146.json in the fl10n repository