From 82e9beb07686f75e91bf180d5b3555801963f271 Mon Sep 17 00:00:00 2001
From: Yaroslav Halchenko <debian@onerussian.com>
Date: Fri, 20 Aug 2021 15:51:37 -0400
Subject: [PATCH 1/4] BF: inform that no to <label> can be identical if casing
 is ignored

---
 src/02-common-principles.md | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/02-common-principles.md b/src/02-common-principles.md
index 9143720496..22f337d11c 100644
--- a/src/02-common-principles.md
+++ b/src/02-common-principles.md
@@ -111,7 +111,9 @@ misunderstanding we clarify them here.
 
 1.  **`<label>`** - an alphanumeric value, possibly prefixed with arbitrary
     number of 0s for consistent indentation, for example, it is `rest` in `task-rest`
-    following `task-<label>` specification.
+    following `task-<label>` specification. **Note:** value is case sensitive, but
+    values for the same entity MUST NOT be identical if casing is ignored, for example,
+    it is not allowed to have `sub-S1` and `sub-s1`.
 
 1.  **`suffix`** - an alphanumeric value, located after the `key-value_` pairs (thus after
     the final `_`), right before the **File extension**, for example, it is `eeg` in

From 958125c690fb92e97b1d7a3601a5f0b2a609aeaf Mon Sep 17 00:00:00 2001
From: Yaroslav Halchenko <debian@onerussian.com>
Date: Tue, 31 Aug 2021 12:54:59 -0400
Subject: [PATCH 2/4] RF: move collision intollerance to subsection of
 "Participant names and other labels"

---
 src/02-common-principles.md | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/src/02-common-principles.md b/src/02-common-principles.md
index 22f337d11c..65a2fd0dfd 100644
--- a/src/02-common-principles.md
+++ b/src/02-common-principles.md
@@ -111,9 +111,7 @@ misunderstanding we clarify them here.
 
 1.  **`<label>`** - an alphanumeric value, possibly prefixed with arbitrary
     number of 0s for consistent indentation, for example, it is `rest` in `task-rest`
-    following `task-<label>` specification. **Note:** value is case sensitive, but
-    values for the same entity MUST NOT be identical if casing is ignored, for example,
-    it is not allowed to have `sub-S1` and `sub-s1`.
+    following `task-<label>` specification.
 
 1.  **`suffix`** - an alphanumeric value, located after the `key-value_` pairs (thus after
     the final `_`), right before the **File extension**, for example, it is `eeg` in
@@ -633,6 +631,11 @@ it refers to. For example `sub-01` refers to the `sub` entity (a
 subject) with the label `01`. The `sub-` prefix is not part of the subject
 label, but must be included in file names (similarly to other key names).
 
+### Case collision intolerance
+
+`<label>` values are sensitive, but values for the same entity MUST NOT be identical across files if casing is ignored.
+For example, it is not allowed to have `sub-S1` and `sub-s1`.
+
 ## Uniform Resource Indicator
 
 A Uniform Resource Indicator (URI) is a string referring to a resource and SHOULD

From 9b74f54e970ad3c0e19cafd2347cfa03425ae4f4 Mon Sep 17 00:00:00 2001
From: Yaroslav Halchenko <debian@onerussian.com>
Date: Tue, 31 Aug 2021 13:00:54 -0400
Subject: [PATCH 3/4] ENH: reference section with more information on labels
 within Definitions.<label>

---
 src/02-common-principles.md | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/02-common-principles.md b/src/02-common-principles.md
index 65a2fd0dfd..18aa9e159d 100644
--- a/src/02-common-principles.md
+++ b/src/02-common-principles.md
@@ -111,7 +111,8 @@ misunderstanding we clarify them here.
 
 1.  **`<label>`** - an alphanumeric value, possibly prefixed with arbitrary
     number of 0s for consistent indentation, for example, it is `rest` in `task-rest`
-    following `task-<label>` specification.
+    following `task-<label>` specification. See [Participant names and other labels](#participant-names-and-other-labels)
+    for additional information.
 
 1.  **`suffix`** - an alphanumeric value, located after the `key-value_` pairs (thus after
     the final `_`), right before the **File extension**, for example, it is `eeg` in

From 6fc37455f11f6b893ef697de60f71e01a49f5c61 Mon Sep 17 00:00:00 2001
From: "Christopher J. Markiewicz" <markiewicz@stanford.edu>
Date: Mon, 13 Sep 2021 12:47:05 -0400
Subject: [PATCH 4/4] ENH: Make case collision intolerance a general file
 naming principle

---
 src/02-common-principles.md | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/src/02-common-principles.md b/src/02-common-principles.md
index 18aa9e159d..8f4404f49c 100644
--- a/src/02-common-principles.md
+++ b/src/02-common-principles.md
@@ -111,8 +111,8 @@ misunderstanding we clarify them here.
 
 1.  **`<label>`** - an alphanumeric value, possibly prefixed with arbitrary
     number of 0s for consistent indentation, for example, it is `rest` in `task-rest`
-    following `task-<label>` specification. See [Participant names and other labels](#participant-names-and-other-labels)
-    for additional information.
+    following `task-<label>` specification. Note that labels MUST not collide when
+    casing is ignored (see [Case collision intolerance](#case-collision-intolerance)).
 
 1.  **`suffix`** - an alphanumeric value, located after the `key-value_` pairs (thus after
     the final `_`), right before the **File extension**, for example, it is `eeg` in
@@ -219,6 +219,15 @@ Use cases concerning this convention are compiled in the
 [file collections](./99-appendices/10-file-collections.md) appendix.
 This convention is mainly intended for but not limited to MRI modalities.
 
+### Case collision intolerance
+
+File name components are case sensitive,
+but collisions MUST be avoided when casing is ignored.
+For example, a dataset cannot contain both `sub-s1` and `sub-S1`,
+as the labels would collide on a case-insensitive filesystem.
+Additionally, because the suffix `eeg` is defined,
+then the suffix `EEG` will not be added to future versions of the standard.
+
 ## Source vs. raw vs. derived data
 
 BIDS was originally designed to describe and apply consistent naming conventions
@@ -632,11 +641,6 @@ it refers to. For example `sub-01` refers to the `sub` entity (a
 subject) with the label `01`. The `sub-` prefix is not part of the subject
 label, but must be included in file names (similarly to other key names).
 
-### Case collision intolerance
-
-`<label>` values are sensitive, but values for the same entity MUST NOT be identical across files if casing is ignored.
-For example, it is not allowed to have `sub-S1` and `sub-s1`.
-
 ## Uniform Resource Indicator
 
 A Uniform Resource Indicator (URI) is a string referring to a resource and SHOULD