That seems to be a typo in the documentation. The changes in X701 only affect the ValRep list of the widgets. Please note that the documentation is handling two different notations:

• Associative List: IdPart=ValuePart
• ValRep List Syntax (for Widgets): Value=Representation

Before X701 the documented limit of the IdPart (Associative List) was 150 bytes and for the Value (Widget ValRep List) it was 80 bytes. With X701 the documented limit of both IDPart and Value is now 511 bytes (although when used in a Widget ValRep List validation of values larger than 289 bytes will fail).

The 511 limit is in the general page "Associative Lists" or if you use the index "lists"->"associative" and states:  

For each item in an associative list:

• The IdPart is limited to 289 bytes; the ValuePart can be 511 bytes .

With the pur 9.7.07 the text in the chm was:

For each item in an associative list:

• The IdPart is limited to 150 bytes; the ValuePart can be any length.

in x702 help, the obfuscating limit to 511 bytes (introduced with x701) is removed on both pages "valrep list syntax" and "associative lists". which contradicts the remark from diseli. But on "Maximums" under the subtitle "limits for components:" we still find some confusing: Length of first value (IdPart) in an associative list item. This is the Value in a ValRep list item.      289 bytes Length of the second value (ValuePart) in an associative list item. This is (the Representation in ValRep list item.         511 bytes   Think it needs some amendments here as well.