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README: clarify monotonicity requirements #62

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README: clarify monotonicity requirements #62

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5 changes: 2 additions & 3 deletions README.md
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Expand Up @@ -134,8 +134,7 @@ Crockford's Base32 is used as shown. This alphabet excludes the letters I, L, O,

### Monotonicity

When generating a ULID within the same millisecond, we can provide some
guarantees regarding sort order. Namely, if the same millisecond is detected, the `random` component is incremented by 1 bit in the least significant bit position (with carrying). For example:
When generating a ULID within the same millisecond, implementations may optionally provide monotonicity by statefully incrementing the `random` component rather than regenerating it.

```javascript
import { monotonicFactory } from 'ulid'
Expand All @@ -147,7 +146,7 @@ ulid() // 01BX5ZZKBKACTAV9WEVGEMMVRZ
ulid() // 01BX5ZZKBKACTAV9WEVGEMMVS0
```

If, in the extremely unlikely event that, you manage to generate more than 2<sup>80</sup> ULIDs within the same millisecond, or cause the random component to overflow with less, the generation will fail.
Generating more than 2<sup>80</sup> ULIDs within the same millisecond, or causing the random component to overflow, will result in an error.

```javascript
import { monotonicFactory } from 'ulid'
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