user: Question: Name the standard yarn weight system for 7 wpi
Columns: ['Standard Yarn Weight System', 'Yarn Type (US)', 'Ply (UK, NZ, AU)', 'm/100g', 'Wraps Per Inch (WPI)']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['0 or Lace', 'Thread, Cobweb and Lace', '1 - 3 ply', '600-800', '18+ wpi']
SQL:

assistant: SELECT "Standard Yarn Weight System" FROM "Table" WHERE "Wraps Per Inch (WPI)" = '7 wpi';