APK2055I DATA IN A PAGEDEF RESOURCE IS NOT VALID: THE ENCODING SCHEME IDENTIFIER FOR THE USER DATA IS NOT SPECIFIED IN THE ENCODING SCHEME TRIPLET ON THE BDM STRUCTURED FIELD.

Explanation The Encoding Scheme Identifier for User Data (ESidUD)
is missing on the Encoding Scheme triplet (X'50') on a Begin Data
Map (BDM) structured field. This information is required when processing
an XML page definition. 

System action ACIF stops processing the current data set and issues
additional messages that identify the processing environment when
the error was found. 

System programmer response If an IBM® licensed
program was used to create the structured fields for the page definition
with the error, verify that the input to that program is valid. If
the input is valid, see the diagnosis reference of your system for
assistance in determining the source of the problem. 

User response You must provide the encoding scheme for the user
data. If the structured field does not have an error, the error might
be an ACIF logic error. If you used a program to create the structured
fields for the page definition, contact your system programmer. 