'Yes'

'Yes' is Truthy

'No'

'No' is Truthy

''

'' is Falsy

NOT ''

'' is Truthy

1

1 is Truthy

0

0 is Falsy

-1

-1 is Truthy

'1'

'1' is Truthy

'0'

'0' is Falsy

'TRUE'

'TRUE' is Truthy

'FALSE'

'FALSE' is Truthy

TRUE

TRUE is Falsy

FALSE

FALSE is Falsy

'NULL'

'NULL' is Truthy

NULL

NULL is Falsy

<mvt:assign name="g.NULL" value="1" />

NULL

NULL is Truthy

'undefined'

'undefined' is Truthy

undefined

undefined is Falsy

<mvt:assign name="g.undefined" value="1" />

undefined

undefined is Truthy

'' IN 'foobar'

'' IN 'foobar' is Truthy