A wallet seed phrase

Money

A recovery phrase is a fixed count of lower case words separated by single spaces, with every word drawn from a fixed list and the last one constrained by a checksum.

The shape

Word count: 12, 13, 24 or 25, depending on the scheme; no other count is a phrase
Case: lower throughout, with no capital anywhere including the first word
Separator: exactly one space between neighbours, and none at either end
Punctuation: none: no commas, no numbering, no quotation marks, no full stop
Vocabulary: every word appears on a fixed published list; a word off the list is not part of a phrase
Last word: constrained by a checksum, so it is not freely chosen

word-01 word-02 word-03 word-04 word-05 word-06
word-07 word-08 word-09 word-10 word-11 word-12

Position markers standing in for a twelve word layout, not entries from any wordlist. A phrase contains no digits and no hyphens, and it occupies one line rather than two. These tokens are here so that nothing on this page can be mistaken for a phrase.

The shape a phrase has

word-01 word-02 word-03 word-04 word-05 word-06 ...

The shape a display gives it

1. Word-01
2. Word-02
3. Word-03

The numbering and the capitals on the right were added by something that displayed the phrase in a list. They are presentation, and they are not part of the phrase.

The word count is the strongest single property, because it is discrete. There is no such thing as a fourteen word phrase or a twenty word phrase; the counts are fixed by the schemes in use, and a count that is not one of them means words have been lost or added. Everything else about the shape follows from the fact that a phrase is meant to be written down by hand and read back: plain lower case, plain spaces, no ornament.

How to check it by eye

Counting gaps, not words

Count the gaps rather than the words. Eleven gaps means twelve words, twenty three means twenty four, and gaps are easier to see than word boundaries in a long line.
Look for a capital letter anywhere in the line. There should be none, including at the start.
Look for anything that is not a letter or a single space: a comma, a number, a bracket, a stray hyphen.
Test for double spaces by moving the caret along the line, or by selecting it; two spaces look like one on almost every screen.

What a wrong shape means

A word that does not appear on the list is decisive: the line is not a phrase. In practice this comes from a spell checker that helpfully replaced an unfamiliar word, from handwriting read back wrongly, or from a transcription that guessed at a letter. It is not something to solve by trying near neighbours until one fits, and this card offers no procedure for doing so.

A count outside the four permitted values means words were dropped or duplicated in transit, most often by a text box that collapsed a line or by a copy that stopped at the edge of a visible area.

Capitals and numbering usually mean the phrase was rendered by something with opinions about lists. Autocapitalisation at the start of a line is so common on small screens that it is worth expecting.

A wrong shape here says the same thing it says elsewhere on this site: something happened to the line between its origin and your screen. It does not say who, and it does not say why.

Where this shape should not be

This is the one shape on this reference where finding it is itself the entire result, before any question of whether it is well formed.

A phrase in a chat window, in a screenshot, in a support form, in a web page text field, in an email draft, in a pasted block of notes, in a photograph of a piece of paper: in each case the shape has already done its work by being visible at all. Nothing in the format distinguishes a phrase read by the person who wrote it from a phrase read by anybody else, because there is nothing in it to distinguish. The words carry no owner and no permission. Whoever reads them reads exactly what you read.

It follows that any page, message or form asking for one is asking for the whole thing, since a phrase has no partial form. There is no version of it that is safe to show for checking purposes, no first three words that mean less than twelve, and no way to demonstrate that you hold one without handing it over. This card prints none, which is why the example above uses hyphenated position markers instead of words.

What a correct shape does not prove

A line of twelve lower case list words with single spaces is a line in the right shape. Consider what is still unsettled.

The order. A set of words can all be on the list and still be in the wrong sequence, and the sequence is not something a reader can see.
The scheme. Several schemes use overlapping vocabularies, so a well formed line does not announce which one produced it.
The origin. Nothing in the shape shows whether the words were generated properly or chosen by a person, and words chosen by a person look identical.
How many copies exist. This is the significant one. The shape is silent on whether the line has been seen, photographed, stored in a chat history or backed up somewhere.
Which wallet it corresponds to. The line does not name one, and no reading of it will.

What this card is not

This is not about secrets you choose, which are described at a password. It is not about secret key material in an armoured block, which is a PGP private key block and looks nothing like a line of words. It offers no procedure for repairing, guessing or completing a phrase, and it will not describe one.