# Synopsis

PDX_MSGT mda_ModifyPtr(MDA_PTR parent, MDA_PTR child, MDA_PTR *old_child)

# Purpose

Modify an entity reference.

# Description

The reference from parent to @a *old_child will be replaced with a reference from parent to child. @a *old_child will be updated with the value of child and parent will be removed from the parent list of @a *old_child. Child may be specified as MDA_NULL_PTR. Calling this function is the same as the following code sequence:

.nf mda_DeletePtr (parent, *old_child); mda_AddPtr (parent, child, old_child); .fi

# Input

## parent

Entity referencing child

## child

Entity referenced from parent

## old_child

Entity currently referenced from parent

# Output

## old_child

Set to value of child

# Return

MDA error code