diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6f1bd37c..3850067b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -28,7 +28,6 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Excellon drill: added `route_mode_for_oval_holes` option.
 - Default global `dir` option.
 - Global option to specify `out_dir` (like -d command line option)
-- Pattern to expand the variant name: %V
 - 3D view render
 - SCH PDF Print: monochrome and no frame options.
 - New expansion patterns:
@@ -40,12 +39,14 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
     **%bF**, **%bp** and **%br** board data
   - **%sc**, **%sC1**, **%sC2**, **%sC3**, **%sC4**, **%sd**, **%sf**,
     **%sF**, **%sp** and **%sr** schematic data
+  - **%V** the variant name
 - Now patterns are also expanded in the out_dir name.
 - Global options to control the date format.
 - Outputs can use the options of other outputs as base (extend them). (#112)
 - Another experimental mechanism to change 3D models according to the variant.
   (#103)
 - A mechanism to avoid running some outputs by default. (#112)
+- New pre-flight command to replace tags in the schematic. (#93)
 
 ### Changed
 - Internal BoM: now components with different Tolerance, Voltage, Current
diff --git a/README.md b/README.md
index cfe19460..083848e0 100644
--- a/README.md
+++ b/README.md
@@ -121,6 +121,24 @@ This section is used to specify tasks that will be executed before generating an
         The report file name is controlled by the global output pattern (%i=drc %x=txt).
 - `run_erc`: [boolean=false] Runs the ERC (Electrical Rules Check). To ensure the schematic is electrically correct.
         The report file name is controlled by the global output pattern (%i=erc %x=txt).
+- `sch_replace`: [dict] Replaces tags in the schematic. I.e. to insert the git hash or last revision date.
+  * Valid keys:
+    - `date_command`: [string=''] Command to get the date to use in the schematic.
+                      git log -1 --format='%as' -- $KIBOT_SCH_NAME
+                      Will return the date in YYYY-MM-DD format.
+                      date -d @`git log -1 --format='%at' -- $KIBOT_SCH_NAME` +%Y-%m-%d_%H-%M-%S
+                      Will return the date in YYYY-MM-DD_HH-MM-SS format.
+    - `replace_tags`: [dict|list(dict)] Tag or tags to replace.
+      * Valid keys:
+        - `after`: [string=''] Text to add after the output of `command`.
+        - `before`: [string=''] Text to add before the output of `command`.
+        - `command`: [string=''] Command to execute to get the text, will be used only if `text` is empty.
+                     KIBOT_SCH_NAME variable is the name of the current sheet.
+                     KIBOT_TOP_SCH_NAME variable is the name of the top sheet.
+        - `tag`: [string=''] Name of the tag to replace. Use `version` for a tag named `@version@`.
+        - `tag_delimiter`: [string='@'] Character used to indicate the beginning and the end of a tag.
+                           Don't change it unless you really know about KiCad's file formats.
+        - `text`: [string=''] Text to insert instead of the tag.
 - `update_xml`: [boolean=false] Update the XML version of the BoM (Bill of Materials).
         To ensure our generated BoM is up to date.
         Note that this isn't needed when using the internal BoM generator (`bom`).
diff --git a/docs/samples/generic_plot.kibot.yaml b/docs/samples/generic_plot.kibot.yaml
index 721867ac..0f5359ab 100644
--- a/docs/samples/generic_plot.kibot.yaml
+++ b/docs/samples/generic_plot.kibot.yaml
@@ -23,6 +23,15 @@ preflight:
   # [boolean=false] Runs the ERC (Electrical Rules Check). To ensure the schematic is electrically correct.
   # The report file name is controlled by the global output pattern (%i=erc %x=txt).
   run_erc: true
+  # [dict] Replaces tags in the schematic. I.e. to insert the git hash or last revision date.
+  sch_replace: 
+    date_command: "git log -1 --format='%as' -- $KIBOT_SCH_NAME"
+    replace_tags:
+      - tag: '@git_hash@'
+        command: 'git log -1 --format="%h" $KIBOT_SCH_NAME'
+        before: 'Git hash: <'
+        after: '>'
+
   # [boolean=false] Update the XML version of the BoM (Bill of Materials).
   # To ensure our generated BoM is up to date.
   # Note that this isn't needed when using the internal BoM generator (`bom`).
diff --git a/kibot/kicad/v5_sch.py b/kibot/kicad/v5_sch.py
index 3f07ff13..6438e978 100644
--- a/kibot/kicad/v5_sch.py
+++ b/kibot/kicad/v5_sch.py
@@ -1397,6 +1397,8 @@ class SchematicSheet(object):
                     raise SchFileError('Malformed sheet file name', line, f)
                 sch.file = m.group(1)
                 sch.file_size = int(m.group(2))
+                if not os.path.isfile(sch.file):
+                    raise SchFileError('Missing sub-sheet `{}`'.format(sch.file), line, f)
             else:
                 sch.labels.append(SchematicPort.parse(line[1:], f))
             line = f.get_line()
diff --git a/kibot/misc.py b/kibot/misc.py
index bac9c2de..9f891e2b 100644
--- a/kibot/misc.py
+++ b/kibot/misc.py
@@ -35,6 +35,7 @@ SVG_SCH_PRINT = 21
 CORRUPTED_SCH = 22
 WRONG_INSTALL = 23
 RENDER_3D_ERR = 24
+FAILED_EXECUTE = 25
 error_level_to_name = ['NONE',
                        'INTERNAL_ERROR',
                        'WRONG_ARGUMENTS',
@@ -60,6 +61,7 @@ error_level_to_name = ['NONE',
                        'CORRUPTED_SCH',
                        'WRONG_INSTALL',
                        'RENDER_3D_ERR',
+                       'FAILED_EXECUTE',
                        ]
 CMD_EESCHEMA_DO = 'eeschema_do'
 URL_EESCHEMA_DO = 'https://github.com/INTI-CMNB/KiAuto'
@@ -208,6 +210,7 @@ W_NOVARIANTS = '(W069) '
 W_NOENDLIB = '(W070) '
 W_NEEDSPCB = '(W071) '
 W_NOGLOBALS = '(W072) '
+W_EMPTREP = '(W073) '
 
 
 class Rect(object):
diff --git a/tests/test_plot/test_preflight.py b/tests/test_plot/test_preflight.py
index 7a2f989c..32dcd430 100644
--- a/tests/test_plot/test_preflight.py
+++ b/tests/test_plot/test_preflight.py
@@ -16,7 +16,10 @@ pytest-3 --log-cli-level debug
 
 import os
 import sys
+import shutil
 import logging
+import re
+from subprocess import run, PIPE
 # Look for the 'utils' module from where the script is running
 prev_dir = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
 if prev_dir not in sys.path:
@@ -156,3 +159,41 @@ def test_update_xml_fail(test_dir):
     ctx = context.TestContext(test_dir, 'Update_XMLFail', prj, 'update_xml', '')
     ctx.run(BOM_ERROR)
     ctx.clean_up()
+
+
+def test_sch_replace_1(test_dir):
+    """ Tags replacements in an schematic """
+    prj = 'test_v5'
+    ctx = context.TestContext(test_dir, 'test_sch_replace_1', prj, 'sch_replace_1', '')
+    ctx.run(extra=[])
+    files = {}
+    file = ctx.sch_file
+    files[file] = file + '-bak'
+    file = ctx.sch_file.replace('test_v5', 'deeper')
+    files[file] = file + '-bak'
+    file = ctx.sch_file.replace('test_v5', 'sub-sheet')
+    files[file] = file + '-bak'
+    for k, v in files.items():
+        assert os.path.isfile(v), v
+        assert os.path.getsize(v) > 0
+    try:
+        for k, v in files.items():
+            logging.debug(k)
+            cmd = ['/bin/bash', '-c', "date -d @`git log -1 --format='%at' -- " + k + "` +%Y-%m-%d_%H-%M-%S"]
+            text = run(cmd, stdout=PIPE, stderr=PIPE, universal_newlines=True).stdout.strip()
+            with open(k, 'rt') as f:
+                c = f.read()
+            m = re.search('^Date \"(.*)\"$', c, re.MULTILINE)
+            logging.debug('Date: ' + text)
+            assert m is not None
+            assert m.group(1) == text
+            if 'test_v5' in k:
+                cmd = ['/bin/bash', '-c', "git log -1 --format='%h' " + k]
+                text = run(cmd, stdout=PIPE, stderr=PIPE, universal_newlines=True).stdout.strip()
+                m = re.search("Git hash: '(.*)'", c)
+                logging.debug('Hash: ' + text)
+                assert m is not None
+                assert m.group(1) == text
+    finally:
+        for k, v in files.items():
+            os.rename(v, k)
diff --git a/tests/yaml_samples/sch_replace_1.kibot.yaml b/tests/yaml_samples/sch_replace_1.kibot.yaml
new file mode 100644
index 00000000..f11a73c6
--- /dev/null
+++ b/tests/yaml_samples/sch_replace_1.kibot.yaml
@@ -0,0 +1,12 @@
+# Example KiBot config file
+kibot:
+  version: 1
+
+preflight:
+  sch_replace:
+    date_command: date -d @`git log -1 --format='%at' -- $KIBOT_SCH_NAME` +%Y-%m-%d_%H-%M-%S
+    replace_tags:
+      - tag: "Comment4"
+        command: git log -1 --format="%h" $KIBOT_SCH_NAME
+        before: "Git hash: '"
+        after: "'"