> For the complete documentation index, see [llms.txt](https://docs.verifone.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.verifone.com/kld/kld-user-guide/user-guide-p400/verifone-kld-ui-description/reference-sets.md).
# Reference Sets
* Please refer to [Key Concepts](/kld/kld-user-guide/user-guide-p400/key-concepts.md#reference-set) to understand reference sets.
* Keys must be created or imported before a reference set can be created. Refer to [Keys](/kld/kld-user-guide/user-guide-p400/verifone-kld-ui-description/keys.md).
* The above reference set listing dialog allows the user to manage Reference Sets.
* To create a reference set, click on the Create button. See "Create Reference Set" section below for more information
* To delete a reference set, click on the "X" button to the right.
* To see the reference set information, click on the reference set name. The dialog below shows the reference set list information.
#### Create Reference Set
* A reference contains a subset of keys imported.
* Each key needs a Key Block Header (KBH).
* A reference set is unique to a platform.
* Reference set create dialog
* Enter a reference set name (32 characters maximum)
* Select a platform (Trinity or Neo or Victa)
* Select signer certificate (to sign the key payload sent to the target terminal).
* Use the "Key" button to select the keys want in this reference set. See Key selection dialog below.
* Use the "KBH" button and set the Key block header for each of keys selected using the Keys button. See KBH Setting dialog below.
* For example, if 3 keys are chosen using "Key" option, the KBH button asks for 3 key block header entries.
* For individual keys like BDK(sent as IK) and Fixed keys, the KBH is per key. Meaning, each Key will have its own KBH.
* Master Session Keys are on a Key List. Each Key List can have one or more individual lists. For each list only one KBH is needed. The KBH will guide the user to enter the data.
* Key Selection Dialog
* Selecting the Key Type check box will display the keys or key lists under that Key type. User can choose keys by scrolling the screen and selecting the check boxes
* For example, the above dialog shows DUKPT-BDK (Sent as IK) and Fixed Key Types are selected. User the "DUKPT-BDK" key type, "BDK-200" Key name is chosen. Scrolling the screen down will show the keys selected under Fixed Key Type.
* After selecting the keys, hit the "Select" button confirm the key selections
* Key Block Header (KBH) Setting Dialog
* The KBH dialogs are shown below.
* For Trinity Platform, slot number is needed.
* For Neo and Victa platforms, Key name on the terminal is needed. Sample dialogs for slot number and key name is shown below.
* For fixed keys user can select Key Usage and the Mode as shown below. D0 for data keys, M0 MAC keys and the corresponding Modes for each key usage.
* Fixed also supports the concept of "K0" and "K1" if some users want to send this fixed to multiple terminals.
* For Master Keys, the key usage is fixed "K0" or "K1". The mode can be selected. D for decrypt, E for encrypt and B for both.
* Key usage "K1" is not currently supported in Trinity Platform.
* The KLD does not prevent the user from selecting and sending the key with "K1" usage to Trinity platform. It will fail or the terminal will ignore it.
* The reason for this is, in future, KLD software does not require a change when the terminal starts supporting "K1" keys.
* For BDK keys Key usage and the Mode is fixed and cannot be changed as shown below. B1 is DUKPT keys and X for Key derivation.
  
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