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ER: Remaining Cardinality Spellings

The other word and symbol spellings mermaid accepts: `only one`, `zero or more`, `one or many`, `many(0)`, `many(1)`, `1+`, `0+`, `zero or one`, and the `to` / `optionally to` connectors. Complements the word-form sample (#1788).

er-remaining-cardinality-spellings.mmd
erDiagram
  AUTHOR only one to zero or more BOOK : writes
  BOOK one or many to many(0) REVIEW : receives
  REVIEW many(1) optionally to 0+ COMMENT : attracts
  COMMENT 1+ to zero or one FLAG : raises
Output
ER diagram, Zombie Mermaid AUTHOR (no attributes) BOOK (no attributes) REVIEW (no attributes) COMMENT (no attributes) FLAG (no attributes) writes receives attracts raises

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