PO release startegy "common issue"

Question

if release strategy cirtera contains item level characterisitc then if po contains multiple line item with differnet values agains that char. then system does not blocks the PO and for time being let us say PLANT / MAterial group as char.
now this issue is encountered by every one but i could not find the solution for this (i know the reason behind this issue but i dont know the precise solution some consultants say to maintain the blank value in char  value but i dont think system accepts blank value for char like plant/material group)
i hope to get some soild reply

Answer 1

so finally this is the solution for the issue
Unfortunately there is no mechanism like entering a blank or * in order to make classification understand this characteristic is not relevant.
The characteristic and its values will always been taken in consideration.
In case you use a 'non-aggregated' field in your release strategy you need to enter all possible values for the corresponding characteristic (as a range - just in case of numeric characteristics).
Example: You use item-wise release strategy for purchase requisitions
  and the plant is used in the release strategy (characteristic
  CEBAN-WERKS).
  Release strategy determination will be processed item by item.
  There will always be just one value for the plant (from the current
  item), multiple values and thus aggregation is not possible.
  In this case you have to enter all possible values for the
  characteristic CEBAN-WERKS.
In case you use an 'aggregated' field in your release strategy (which is possible for overall release strategy for PRs and release strategy for POs) and multiple values are used for that field on a purchasing document, you can use a blank value for the corresponding characteristic if you'd like the release strategy be applied.
Example: You use release strategy for a PO and the plant is one of the
  relevant fields (characteristic CEKKO-WERKS).
  You enter a first PO item with plant 0001 and a second item with plant
  0002.
  Since there are multiple values for the plant the system will
  'aggregate' to blank value and use blank value for searching for a
  release strategy.
  Since you have maintained a blank value for characteristic
  CEKKO-WERKS the system will find the corresponding release strategy.
In this case please pay attention to note 732566.
It causes an error in case blank values are used for release strategies.
Even when the long text just talks about process orders the impact of the side effect is more general.
Please take care note 754178 is implemented, it corrects note 732566.