SharePoint - Deploy custom field

In SharePoint (2007), custom fields — custom column types you can add to lists — are deployed through 3 steps:

• Install the signed assembly in the GAC,
• Deploy the fldtypes*.xml to \12\TEMPLATE\XML,
• Deploy the *.ascx without it's .cs to \12\TEMPLATE\CONTROLTEMPLATES.

After an IISRESET the thing should then work.

Notes on custom fields, e.g. for the error Type X not found:

• Make sure the DefaultTemplateName matches the ID of the RenderingTemplate.