diff --git a/CITATION.cff b/CITATION.cff
index b733e5d..4a68f21 100644
--- a/CITATION.cff
+++ b/CITATION.cff
@@ -1,15 +1,32 @@
-cff-version: 1.2.0
-message: "If you use this software, please cite it as below."
+# This CITATION.cff file was generated with cffinit.
+# Visit https://bit.ly/cffinit to generate yours today!
 
-title: "dems"
-abstract: "DESHIMA measurement set by DataArray"
-version: 2024.7.2
-date-released: 2024-07-17
-license: "MIT"
-doi: "10.5281/zenodo.8151950"
-url: "https://github.com/deshima-dev/dems"
+cff-version: 1.2.0
+title: dems
+message: >-
+  If you use this software, please cite it using the
+  metadata from this file.
+type: software
 authors:
-  - given-names: "Akio"
-    family-names: "Taniguchi"
-    affiliation: "Nagoya University"
-    orcid: "https://orcid.org/0000-0002-9695-6183"
+  - given-names: Akio
+    family-names: Taniguchi
+    email: taniguchi.akio@gmail.com
+    affiliation: Kitami Institute of Technology
+    orcid: 'https://orcid.org/0000-0002-9695-6183'
+identifiers:
+  - type: doi
+    value: 10.5281/zenodo.8151950
+repository-code: 'https://github.com/deshima-dev/dems'
+url: 'https://github.com/deshima-dev/dems'
+abstract: DESHIMA Measurement Set
+keywords:
+  - python
+  - astronomy
+  - data-format
+  - deshima
+  - measurement-set
+  - spectroscopy
+  - submillimeter
+license: MIT
+version: 2025.6.0
+date-released: '2025-06-16'
diff --git a/LICENSE b/LICENSE
index 9de016d..74c44cb 100644
--- a/LICENSE
+++ b/LICENSE
@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) 2022-2024 Akio Taniguchi
+Copyright (c) 2022-2025 Akio Taniguchi
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
diff --git a/README.md b/README.md
index 6a05028..507840f 100644
--- a/README.md
+++ b/README.md
@@ -11,7 +11,7 @@ DESHIMA measurement set by DataArray
 ## Installation
 
 ```shell
-pip install dems==2024.7.2
+pip install dems==2025.6.0
 ```
 
 ## Usage
@@ -40,10 +40,11 @@ da = MS.new(
 |  | name | Name | DEMS name | - | "DEMS" | str | - | - |
 | Dimensions | time | Dimension | Start time in UTC | - | 1970-01-01T00:00:00.000000000 | numpy.ndarray | (time,) | datetime64[ns] |
 |  | chan | Dimension | Channel ID | - | 0 | numpy.ndarray | (chan,) | int64 |
-| Labels | beam | Coordinate | Beam label | - | "" | numpy.ndarray | (time,) | str (<U16) |
+| Labels | observation | Coordinate | Observation label | - | "" | numpy.ndarray | (time,) | str (<U16) |
 |  | scan | Coordinate | Scan label | - | "" | numpy.ndarray | (time,) | str (<U16) |
 |  | subscan | Coordinate | Sub-scan label | - | "" | numpy.ndarray | (time,) | str (<U16) |
 |  | state | Coordinate | State label | - | "" | numpy.ndarray | (time,) | str (<U16) |
+|  | beam | Coordinate | Beam label | - | "" | numpy.ndarray | (time,) | str (<U16) |
 | Telescope pointing | lon | Coordinate | Sky longitude | deg | 0.0 | numpy.ndarray | (time,) | float64 |
 |  | lat | Coordinate | Sky latitude | deg | 0.0 | numpy.ndarray | (time,) | float64 |
 |  | lon_origin | Coordinate | Reference sky longitude | deg | 0.0 | numpy.ndarray | (time,) | float64 |
@@ -62,8 +63,7 @@ da = MS.new(
 |  | beam_pa | Coordinate | Beam position angle | deg | 0.0 | numpy.ndarray | (chan,) | float64 |
 |  | exposure | Coordinate | Sample exposure time | s | 0.0 | numpy.ndarray | () | float64 |
 |  | interval | Coordinate | Sample interval time | s | 0.0 | numpy.ndarray | () | float64 |
-| Observation information | observation | Attribute | Observation name | - | "" | str | - | - |
-|  | observer | Attribute | Observer name | - | "" | str | - | - |
+| Observation information | observer | Attribute | Observer name | - | "" | str | - | - |
 |  | project | Attribute | Project name | - | "" | str | - | - |
 |  | object | Attribute | Object name | - | "" | str | - | - |
 |  | telescope_name | Attribute | Telescope name | - | "" | str | - | - |
diff --git a/dems/__init__.py b/dems/__init__.py
index c2635f4..8117dd2 100644
--- a/dems/__init__.py
+++ b/dems/__init__.py
@@ -1,5 +1,5 @@
 __all__ = ["d1", "d2"]
-__version__ = "2024.7.2"
+__version__ = "2025.6.0"
 
 
 # submodules
diff --git a/dems/d2.py b/dems/d2.py
index 392d008..e61ffab 100644
--- a/dems/d2.py
+++ b/dems/d2.py
@@ -70,9 +70,9 @@ class Weight:
 
 
 @dataclass
-class Beam:
+class Observation:
     data: Data[Ti, Literal["U16"]]
-    long_name: Attr[str] = "Beam label"
+    long_name: Attr[str] = "Observation label"
 
 
 @dataclass
@@ -93,6 +93,12 @@ class State:
     long_name: Attr[str] = "State label"
 
 
+@dataclass
+class Beam:
+    data: Data[Ti, Literal["U16"]]
+    long_name: Attr[str] = "Beam label"
+
+
 @dataclass
 class Lon:
     data: Data[Ti, float]
@@ -366,10 +372,11 @@ class MS(AsDataArray):
     time: Coordof[Time_] = "1970-01-01T00:00:00"
     chan: Coordof[Chan_] = 0
     # labels
-    beam: Coordof[Beam] = ""
+    observation: Coordof[Observation] = ""
     scan: Coordof[Scan] = ""
     subscan: Coordof[Subscan] = ""
     state: Coordof[State] = ""
+    beam: Coordof[Beam] = ""
     # telescope pointing
     lon: Coordof[Lon] = 0.0
     lat: Coordof[Lat] = 0.0
@@ -392,7 +399,6 @@ class MS(AsDataArray):
     exposure: Coordof[Exposure] = 0.0
     interval: Coordof[Interval] = 0.0
     # observation information
-    observation: Attr[str] = ""
     observer: Attr[str] = ""
     project: Attr[str] = ""
     object: Attr[str] = ""
@@ -459,7 +465,6 @@ class Cube(AsDataArray):
     beam_minor: Coordof[BeamMinor] = 0.0
     beam_pa: Coordof[BeamPa] = 0.0
     # observation information
-    observation: Attr[str] = ""
     observer: Attr[str] = ""
     project: Attr[str] = ""
     object: Attr[str] = ""
diff --git a/pyproject.toml b/pyproject.toml
index f3efba1..32398ca 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "dems"
-version = "2024.7.2"
+version = "2025.6.0"
 description = "DESHIMA Measurement Set"
 readme = "README.md"
 keywords = [